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Sample records for single satellite toa

  1. CERES Monthly Gridded Single Satellite TOA and Surfaces/Clouds (SFC) data in HDF (CER_SFC_Terra-FM1-MODIS_Edition2B)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly Gridded TOA/Surface Fluxes and Clouds (SFC) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SFC is also produced for combinations of scanner instruments. All instantaneous shortwave, longwave, and window fluxes at the Top-of-the-Atmosphere (TOA) and surface from the CERES SSF product for a month are sorted by 1-degree spatial regions and by the local hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the SFC along with other flux statistics and scene information. These average fluxes are given for both clear-sky and total-sky scenes. The regional cloud properties are column averaged and are included on the SFC. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2003-10-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=100] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  2. CERES Monthly Gridded Single Satellite TOA and Surfaces/Clouds (SFC) data in HDF (CER_SFC_Terra-FM2-MODIS_Edition2A)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly Gridded TOA/Surface Fluxes and Clouds (SFC) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SFC is also produced for combinations of scanner instruments. All instantaneous shortwave, longwave, and window fluxes at the Top-of-the-Atmosphere (TOA) and surface from the CERES SSF product for a month are sorted by 1-degree spatial regions and by the local hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the SFC along with other flux statistics and scene information. These average fluxes are given for both clear-sky and total-sky scenes. The regional cloud properties are column averaged and are included on the SFC. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2003-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=100] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  3. CERES Monthly Gridded Single Satellite TOA and Surfaces/Clouds (SFC) data in HDF (CER_SFC_Aqua-FM3-MODIS_Edition2A)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly Gridded TOA/Surface Fluxes and Clouds (SFC) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SFC is also produced for combinations of scanner instruments. All instantaneous shortwave, longwave, and window fluxes at the Top-of-the-Atmosphere (TOA) and surface from the CERES SSF product for a month are sorted by 1-degree spatial regions and by the local hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the SFC along with other flux statistics and scene information. These average fluxes are given for both clear-sky and total-sky scenes. The regional cloud properties are column averaged and are included on the SFC. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=100] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  4. CERES Monthly Gridded Single Satellite TOA and Surfaces/Clouds (SFC) data in HDF (CER_SFC_Terra-FM2-MODIS_Edition2C)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly Gridded TOA/Surface Fluxes and Clouds (SFC) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SFC is also produced for combinations of scanner instruments. All instantaneous shortwave, longwave, and window fluxes at the Top-of-the-Atmosphere (TOA) and surface from the CERES SSF product for a month are sorted by 1-degree spatial regions and by the local hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the SFC along with other flux statistics and scene information. These average fluxes are given for both clear-sky and total-sky scenes. The regional cloud properties are column averaged and are included on the SFC. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=100] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  5. CERES Monthly Gridded Single Satellite TOA and Surfaces/Clouds (SFC) data in HDF (CER_SFC_TRMM-PFM-VIRS_Beta4)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly Gridded TOA/Surface Fluxes and Clouds (SFC) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SFC is also produced for combinations of scanner instruments. All instantaneous shortwave, longwave, and window fluxes at the Top-of-the-Atmosphere (TOA) and surface from the CERES SSF product for a month are sorted by 1-degree spatial regions and by the local hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the SFC along with other flux statistics and scene information. These average fluxes are given for both clear-sky and total-sky scenes. The regional cloud properties are column averaged and are included on the SFC. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2000-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=100] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 hour; Temporal_Resolution_Range=Hourly - < Daily].

  6. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Aqua-FM4-MODIS_Edition1B)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop

  7. CERES Single Satellite Footprint, TOA and Surface Fluxes, Clouds (SSF) data in HDF (CER_SSF_Aqua-FM4-MODIS_Ed2A-NoSW)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop

  8. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF)- Test data in HDF (CER_SSF_TRMM-PFM-VIRS_Subset-Edition1)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop

  9. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Terra-FM2-MODIS_Edition2A)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop

  10. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Terra-FM1-MODIS_Edition2A)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop

  11. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_Terra-FM2-MODIS_Edition2B)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop

  12. CERES Single Scanner Satellite Footprint, TOA, Surface Fluxes and Clouds (SSF) data in HDF (CER_SSF_TRMM-PFM-VIRS_Edition1)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop

  13. CERES Single Satellite Footprint, TOA and Surface Fluxes, Clouds (SSF) data in HDF (CER_SSF_Aqua-FM4-MODIS_Edition2A)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product contains one hour of instantaneous Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SSF combines instantaneous CERES data with scene information from a higher-resolution imager such as Visible/Infrared Scanner (VIRS) on TRMM or Moderate-Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Scene identification and cloud properties are defined at the higher imager resolution and these data are averaged over the larger CERES footprint. For each CERES footprint, the SSF contains the number of cloud layers and for each layer the cloud amount, height, temperature, pressure, optical depth, emissivity, ice and liquid water path, and water particle size. The SSF also contains the CERES filtered radiances for the total, shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW, LW, and WN radiances at spacecraft altitude are converted to Top-of-the-Atmosphere (TOA) fluxes based on the imager defined scene. These TOA fluxes are used to estimate surface fluxes. Only footprints with adequate imager coverage are included on CER_SSF_TRMM-PFM-VIRS_Subset_Edition1the SSF which is much less than the full set of footprints on the CERES ES-8 product. The following CERES SSF data sets are currently available: CER_SSF_TRMM-PFM-VIRS_Edition1 CER_SSF_TRMM-PFM-VIRS_Subset_Edition1 CER_SSF_TRMM-PFM-VIRS_Edition2A CER_SSF_TRMM-SIM-VIRS_Edition2_VIRSonly CER_SSF_TRMM-PFM-VIRS_Edition2A-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B-TransOps CER_SSF_TRMM-PFM-VIRS_Edition2B CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition1A CER_SSF_Terra-FM1-MODIS_Edition2A CER_SSF_Terra-FM2-MODIS_Edition2A CER_SSF_Terra-FM1-MODIS_Edition2B CER_SSF_Terra-FM2-MODIS_Edition2B CER_SSF_Aqua-FM4-MODIS_Beta1 CER_SSF_Aqua-FM3-MODIS_Beta2 CER_SSF_Aqua-FM4-MODIS_Beta2. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop

  14. Defining the Magnitude: Patterns, Regularities and Direct TOA-Surface Flux Relationships in the 15-Year Long CERES Satellite Data — Observations, Model and Theory

    Science.gov (United States)

    Zagoni, M.

    2017-12-01

    Over the past fifteen years, the NASA Clouds and the Earth's Radiant Energy System (CERES) satellite mission has provided the scientific community with the most reliable Earth radiation budget data. This presentation offers quantitative assessment of the published CERES Energy Balanced and Filled (EBAF) Edition 2.8 and Edition 4.0 data products, and reveals several internal patterns, ratios and regularities within the annual global mean flux components of the all-sky and clear-sky surface and atmospheric energy budgets. The found patterns, among others, include: (i) direct relationships between the top-of-atmosphere (TOA) radiative and surface radiative and non-radiative fluxes (contradicting the expectation that TOA and surface fluxes are physically decoupled); (ii) integer ratios and relationships between the absorbed and emitted surface and atmospheric energy flow elements; and (iii) definite connections among the clear-sky and the all-sky shortwave, longwave and non-radiative (turbulent) flux elements and the corresponding greenhouse effect. Comparison between the EBAF Ed2.8 and Ed4.0 SFC and TOA data products and trend analyses of the normalized clear-sky and all-sky greenhouse factors are presented. Longwave cloud radiative effect (LW CRE) proved to be playing a principal role in organizing the found numerical patterns in the surface and atmospheric energy flow components. All of the revealed structures are quantitatively valid within the one-sigma range of uncertainty of the involved individual flux elements. This presentation offers a conceptual framework to interpret the found relationships and shows how the observed CERES fluxes can be deduced from this proposed physical model. An important conclusion drawn from our analysis is that the internal atmospheric and surface energy flow system forms a definite structure and seems to be more constrained to the incoming solar energy than previously thought.

  15. Evaluation of Daytime Evaporative Fraction from MODIS TOA Radiances Using FLUXNET Observations

    Directory of Open Access Journals (Sweden)

    Jian Peng

    2014-06-01

    Full Text Available In recent decades, the land surface temperature/vegetation index (LST/NDVI feature space has been widely used to estimate actual evapotranspiration (ETa or evaporative fraction (EF, defined as the ratio of latent heat flux to surface available energy. Traditionally, it is essential to pre-process satellite top of atmosphere (TOA radiances to obtain LST before estimating EF. However, pre-processing TOA radiances is a cumbersome task including corrections for atmospheric, adjacency and directional effects. Based on the contextual relationship between LST and NDVI, some studies proposed the direct use of TOA radiances instead of satellite retrieved LST products to estimate EF, and found that use of TOA radiances is applicable in some regional studies. The purpose of the present study is to test the robustness of the TOA radiances based EF estimation scheme over different climatic and surface conditions. Flux measurements from 16 FLUXNET (a global network of eddy covariance towers sites were used to validate the Moderate Resolution Imaging Spectro radiometer (MODIS TOA radiances estimated daytime EF. It is found that the EF estimates perform well across a wide variety of climate and biome types—Grasslands, crops, cropland/natural vegetation mosaic, closed shrublands, mixed forest, deciduous broadleaf forest, and savannas. The overall mean bias error (BIAS, mean absolute difference (MAD, root mean square difference (RMSD and correlation coefficient (R values for all the sites are 0.018, 0.147, 0.178 and 0.590, respectively, which are comparable with published results in the literature. We conclude that the direct use of measured TOA radiances instead of LST to estimate daytime EF can avoid complex atmospheric corrections associated with the satellite derived products, and would facilitate the relevant applications where minimum pre-processing is important.

  16. The artificial satellite observation chronograph controlled by single chip microcomputer.

    Science.gov (United States)

    Pan, Guangrong; Tan, Jufan; Ding, Yuanjun

    1991-06-01

    The instrument specifications, hardware structure, software design, and other characteristics of the chronograph mounting on a theodolite used for artificial satellite observation are presented. The instrument is a real time control system with a single chip microcomputer.

  17. Single versus mixture Weibull distributions for nonparametric satellite reliability

    International Nuclear Information System (INIS)

    Castet, Jean-Francois; Saleh, Joseph H.

    2010-01-01

    Long recognized as a critical design attribute for space systems, satellite reliability has not yet received the proper attention as limited on-orbit failure data and statistical analyses can be found in the technical literature. To fill this gap, we recently conducted a nonparametric analysis of satellite reliability for 1584 Earth-orbiting satellites launched between January 1990 and October 2008. In this paper, we provide an advanced parametric fit, based on mixture of Weibull distributions, and compare it with the single Weibull distribution model obtained with the Maximum Likelihood Estimation (MLE) method. We demonstrate that both parametric fits are good approximations of the nonparametric satellite reliability, but that the mixture Weibull distribution provides significant accuracy in capturing all the failure trends in the failure data, as evidenced by the analysis of the residuals and their quasi-normal dispersion.

  18. Velocity estimation of an airplane through a single satellite image

    Institute of Scientific and Technical Information of China (English)

    Zhuxin Zhao; Gongjian Wen; Bingwei Hui; Deren Li

    2012-01-01

    The motion information of a moving target can be recorded in a single image by a push-broom satellite. A push-broom satellite image is composed of many image lines sensed at different time instants. A method to estimate the velocity of a flying airplane from a single image based on the imagery model of the linear push-broom sensor is proposed. Some key points on the high-resolution image of the plane are chosen to determine the velocity (speed and direction). The performance of the method is tested and verified by experiments using a WorldView-1 image.%The motion information of a moving target can be recorded in a single image by a push-broom satellite.A push-broom satellite image is composed of many image lines sensed at different time instants.A method to estimate the velocity of a flying airplane from a single image based on the imagery model of the linear push-broom sensor is proposed.Some key points on the high-resolution image of the plane are chosen to determine the velocity (speed and direction).The performance of the method is tested and verified by experiments using a WorldView-1 image.

  19. MERRA 2D IAU Diagnostic, Radiation Surface and TOA, Diurnal (2/3x1/2L1) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MATUNXRAD or tavgU_2d_rad_Nx data product is the MERRA Data Assimilation System 2-Dimensional surface and TOA radiation flux that is time averaged single-level...

  20. MERRA 2D IAU Diagnostic, Radiation Surface and TOA, Monthly Mean (2/3x1/2L1) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MATMNXRAD or tavgM_2d_rad_Nx data product is the MERRA Data Assimilation System 2-Dimensional surface and TOA radiation flux that is time averaged single-level...

  1. TOA Radiation Balance Study through Reprocessed ERBS WFOV Nonscanner data from 1985 to 1998

    Science.gov (United States)

    Shrestha, A. K.; Kato, S.; Wong, T.; Stackhouse, P. W., Jr.; Doelling, D. R.; Loughman, R. P.

    2017-12-01

    Wide-field-of-view (WFOV) nonscanner instrument onboard Earth Radiation Budget Satellite (ERBS) provided broadband irradiances at the top-of-atmosphere (TOA) from 1985 to 1999. However, earlier studies show that the uncertainty in this TOA radiation dataset is significantly higher during the period after the Mt. Pinatubo eruption and battery issue in 1991. In addition, the difference between daytime and nighttime longwave irradiance drifts with time throughout the lifetime of the instrument. We re-processed ERBS WFOV data using the algorithm similar to the one used in the CERES project and calibrated it with CERES-derived irradiances. In addition, the spatial coverage of ERBS irradiances is extended to global from near-global (60°N to 60°S latitudes) using CERES climatological ratio of the near-global to global mean irradiances. The near-global standard deviation of deseasonalized shortwave anomalies computed with Ed4 decreases to 3.2 Wm-2 from 8.0 Wm-2, computed with previous version. In addition, the drift of day-minus-night longwave irradiance is reduced by one third. Similar to the previous version, however, the Ed4 global shortwave irradiance averaged over the 1994 to 1997 period (second period) is smaller by 2.2 Wm-2 compared to that averaged over the 1985 to 1989 period (first period). In addition, the global longwave irradiance in the second period is larger by 0.7 Wm-2 compared to that averaged over the first period. When the difference of two periods is computed (second period minus first period) with the DEEP-C data product (Allan et al. 2014), the difference is 0.5 (-0.3) Wm-2 for shortwave (longwave). The global net imbalance at the TOA computed with ERBS and DEEP-C data sets are, respectively, 0.45 (1.89) Wm-2 and 0.17 (0.96) Wm-2 for the first (second) period. The net imbalance for the CERES period in the 2000s is 0.65 Wm-2. In this presentation, we will further compare Ed4 ERBS-derived TOA net imbalance with ocean heating rates. Re-processed ERBS

  2. Application of Matrix Pencil Algorithm to Mobile Robot Localization Using Hybrid DOA/TOA Estimation

    Directory of Open Access Journals (Sweden)

    Lan Anh Trinh

    2012-12-01

    Full Text Available Localization plays an important role in robotics for the tasks of monitoring, tracking and controlling a robot. Much effort has been made to address robot localization problems in recent years. However, despite many proposed solutions and thorough consideration, in terms of developing a low-cost and fast processing method for multiple-source signals, the robot localization problem is still a challenge. In this paper, we propose a solution for robot localization with regards to these concerns. In order to locate the position of a robot, both the coordinate and the orientation of a robot are necessary. We develop a localization method using the Matrix Pencil (MP algorithm for hybrid detection of direction of arrival (DOA and time of arrival (TOA. TOA of the signal is estimated for computing the distance between the mobile robot and a base station (BS. Based on the distance and the estimated DOA, we can estimate the mobile robot's position. The characteristics of the algorithm are examined through analysing simulated experiments and the results demonstrate the advantages of our method over previous works in dealing with the above challenges. The method is constructed based on the low-cost infrastructure of radio frequency devices; the DOA/TOA estimation is performed with just single value decomposition for fast processing. Finally, the MP algorithm combined with tracking using a Kalman filter allows our proposed method to locate the positions of multiple source signals.

  3. Satellites

    International Nuclear Information System (INIS)

    Burns, J.A.; Matthews, M.S.

    1986-01-01

    The present work is based on a conference: Natural Satellites, Colloquium 77 of the IAU, held at Cornell University from July 5 to 9, 1983. Attention is given to the background and origins of satellites, protosatellite swarms, the tectonics of icy satellites, the physical characteristics of satellite surfaces, and the interactions of planetary magnetospheres with icy satellite surfaces. Other topics include the surface composition of natural satellites, the cratering of planetary satellites, the moon, Io, and Europa. Consideration is also given to Ganymede and Callisto, the satellites of Saturn, small satellites, satellites of Uranus and Neptune, and the Pluto-Charon system

  4. tavgM_2d_rad_Nx: MERRA 2D IAU Diagnostic, Radiation Surface and TOA, Monthly Mean 0.667 x 0.5 degree V5.2.0 (MATMNXRAD) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The MATMNXRAD or tavgM_2d_rad_Nx data product is the MERRA Data Assimilation System 2-Dimensional surface and TOA radiation flux that is time averaged single-level...

  5. Black carbon radiative forcing at TOA decreased during aging.

    Science.gov (United States)

    Wu, Yu; Cheng, Tianhai; Zheng, Lijuan; Chen, Hao

    2016-12-05

    During aging processing, black carbon (also called soot) particles may tend to be mixed with other aerosols, and highly influence their radiative forcing. In this study, freshly emitted soot particles were simulated as fractal aggregates composed of small spherical primary monomers. After aging in the atmosphere, soot monomers were coated by a thinly layer of sulfate as thinly coated soot particles. These soot particles were entirely embedded into large sulfate particle by further aging, and becoming heavily coated soot particles. In clear-sky conditions, black carbon radiative forcing with different aging states were investigated for the bottom and top of atmosphere (BOA and TOA). The simulations showed that black carbon radiative forcing increased at BOA and decreased at TOA after their aging processes. Thinly and heavily coated states increased up to ~12% and ~35% black carbon radiative forcing at BOA, and black carbon radiative forcing at TOA can reach to ~20% and ~100% smaller for thinly and heavily coated states than those of freshly emitted states, respectively. The effect of aging states of black carbon radiative forcing was varied with surface albedo, aerosol optical depth and solar zenith angles. These findings would be helpful for the assessments of climate change.

  6. MERRA 2D IAU Diagnostic, Radiation Surface and TOA, Time Average 1-hourly (2/3x1/2L1) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT1NXRAD or tavg1_2d_rad_Nx data product is the MERRA Data Assimilation System 2-Dimensional surface and TOA radiation flux that is time averaged single-level...

  7. Causal relationships between solar proton events and single event upsets for communication satellites

    Science.gov (United States)

    Lohmeyer, W. Q.; Cahoy, K.; Liu, Shiyang

    In this work, we analyze a historical archive of single event upsets (SEUs) maintained by Inmarsat, one of the world's leading providers of global mobile satellite communications services. Inmarsat has operated its geostationary communication satellites and collected extensive satellite anomaly and telemetry data since 1990. Over the course of the past twenty years, the satellites have experienced more than 226 single event upsets (SEUs), a catch-all term for anomalies that occur in a satellite's electronics such as bit-flips, trips in power supplies, and memory changes in attitude control systems. While SEUs are seemingly random and difficult to predict, we correlate their occurrences to space weather phenomena, and specifically show correlations between SEUs and solar proton events (SPEs). SPEs are highly energetic protons that originate from solar coronal mass ejections (CMEs). It is thought that when these particles impact geostationary (GEO) satellites they can cause SEUs as well as solar array degradation. We calculate the associated statistical correlations that each SEU occurs within one day, one week, two weeks, and one month of 10 MeV SPEs between 10 - 10,000 particle flux units (pfu). However, we find that SPEs are most prevalent at solar maximum and that the SEUs on Inmarsat's satellites occur out of phase with the solar maximum. Ultimately, this suggests that SPEs are not the primary cause of the Inmarsat SEUs. A better understanding of the causal relationship between SPEs and SEUs will help the satellite communications industry develop component and operational space weather mitigation techniques as well as help the space weather community to refine radiation models.

  8. Single-event burnout of power MOSFET devices for satellite application

    International Nuclear Information System (INIS)

    Xue Yuxiong; Tian Kai; Cao Zhou; Yang Shiyu; Liu Gang; Cai Xiaowu; Lu Jiang

    2008-01-01

    Single-event burnout (SEB) sensitivity was tested for power MOSFET devices, JTMCS081 and JTMCS062, which were made in Institute of Microelectronics, Chinese Academy of Sciences, using californium-252 simulation source. SEB voltage threshold was found for devices under test (DUT). It is helpful for engineers to choose devices used in satellites. (authors)

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

    Directory of Open Access Journals (Sweden)

    Ghangho Kim

    2015-04-01

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

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

    Science.gov (United States)

    Kim, Ghangho; Kim, Chongwon; Kee, Changdon

    2015-01-01

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

  11. CERES Monthly TOA and SRB Averages (SRBAVG) data in HDF-EOS Grid (CER_SRBAVG_TRMM-PFM-VIRS_Edition2B)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly TOA/Surface Averages (SRBAVG) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SRBAVG is also produced for combinations of scanner instruments. The monthly average regional flux is estimated using diurnal models and the 1-degree regional fluxes at the hour of observation from the CERES SFC product. A second set of monthly average fluxes are estimated using concurrent diurnal information from geostationary satellites. These fluxes are given for both clear-sky and total-sky scenes and are spatially averaged from 1-degree regions to 1-degree zonal averages and a global average. For each region, the SRBAVG also contains hourly average fluxes for the month and an overall monthly average. The cloud properties from SFC are column averaged and are included on the SRBAVG. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-02-01; Stop_Date=2000-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

  12. CERES Monthly TOA and SRB Averages (SRBAVG) data in HDF-EOS Grid (CER_SRBAVG_Terra-FM1-MODIS_Edition2D)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly TOA/Surface Averages (SRBAVG) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SRBAVG is also produced for combinations of scanner instruments. The monthly average regional flux is estimated using diurnal models and the 1-degree regional fluxes at the hour of observation from the CERES SFC product. A second set of monthly average fluxes are estimated using concurrent diurnal information from geostationary satellites. These fluxes are given for both clear-sky and total-sky scenes and are spatially averaged from 1-degree regions to 1-degree zonal averages and a global average. For each region, the SRBAVG also contains hourly average fluxes for the month and an overall monthly average. The cloud properties from SFC are column averaged and are included on the SRBAVG. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-02-01; Stop_Date=2004-05-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

  13. CERES Monthly TOA and SRB Averages (SRBAVG) data in HDF-EOS Grid (CER_SRBAVG_Terra-FM1-MODIS_Edition2C)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly TOA/Surface Averages (SRBAVG) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SRBAVG is also produced for combinations of scanner instruments. The monthly average regional flux is estimated using diurnal models and the 1-degree regional fluxes at the hour of observation from the CERES SFC product. A second set of monthly average fluxes are estimated using concurrent diurnal information from geostationary satellites. These fluxes are given for both clear-sky and total-sky scenes and are spatially averaged from 1-degree regions to 1-degree zonal averages and a global average. For each region, the SRBAVG also contains hourly average fluxes for the month and an overall monthly average. The cloud properties from SFC are column averaged and are included on the SRBAVG. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-02-01; Stop_Date=2003-02-28] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

  14. CERES Monthly TOA and SRB Averages (SRBAVG) data in HDF-EOS Grid (CER_SRBAVG_Terra-FM2-MODIS_Edition2C)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The Monthly TOA/Surface Averages (SRBAVG) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The SRBAVG is also produced for combinations of scanner instruments. The monthly average regional flux is estimated using diurnal models and the 1-degree regional fluxes at the hour of observation from the CERES SFC product. A second set of monthly average fluxes are estimated using concurrent diurnal information from geostationary satellites. These fluxes are given for both clear-sky and total-sky scenes and are spatially averaged from 1-degree regions to 1-degree zonal averages and a global average. For each region, the SRBAVG also contains hourly average fluxes for the month and an overall monthly average. The cloud properties from SFC are column averaged and are included on the SRBAVG. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-02-01; Stop_Date=2003-02-28] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

  15. Ranging error analysis of single photon satellite laser altimetry under different terrain conditions

    Science.gov (United States)

    Huang, Jiapeng; Li, Guoyuan; Gao, Xiaoming; Wang, Jianmin; Fan, Wenfeng; Zhou, Shihong

    2018-02-01

    Single photon satellite laser altimeter is based on Geiger model, which has the characteristics of small spot, high repetition rate etc. In this paper, for the slope terrain, the distance of error's formula and numerical calculation are carried out. Monte Carlo method is used to simulate the experiment of different terrain measurements. The experimental results show that ranging accuracy is not affected by the spot size under the condition of the flat terrain, But the inclined terrain can influence the ranging error dramatically, when the satellite pointing angle is 0.001° and the terrain slope is about 12°, the ranging error can reach to 0.5m. While the accuracy can't meet the requirement when the slope is more than 70°. Monte Carlo simulation results show that single photon laser altimeter satellite with high repetition rate can improve the ranging accuracy under the condition of complex terrain. In order to ensure repeated observation of the same point for 25 times, according to the parameters of ICESat-2, we deduce the quantitative relation between the footprint size, footprint, and the frequency repetition. The related conclusions can provide reference for the design and demonstration of the domestic single photon laser altimetry satellite.

  16. Thermal radiation analysis for small satellites with single-node model using techniques of equivalent linearization

    International Nuclear Information System (INIS)

    Anh, N.D.; Hieu, N.N.; Chung, P.N.; Anh, N.T.

    2016-01-01

    Highlights: • Linearization criteria are presented for a single-node model of satellite thermal. • A nonlinear algebraic system for linearization coefficients is obtained. • The temperature evolutions obtained from different methods are explored. • The temperature mean and amplitudes versus the heat capacity are discussed. • The dual criterion approach yields smaller errors than other approximate methods. - Abstract: In this paper, the method of equivalent linearization is extended to the thermal analysis of satellite using both conventional and dual criteria of linearization. These criteria are applied to a differential nonlinear equation of single-node model of the heat transfer of a small satellite in the Low Earth Orbit. A system of nonlinear algebraic equations for linearization coefficients is obtained in the closed form and then solved by the iteration method. The temperature evolution, average values and amplitudes versus the heat capacity obtained by various approaches including Runge–Kutta algorithm, conventional and dual criteria of equivalent linearization, and Grande's approach are compared together. Numerical results reveal that temperature responses obtained from the method of linearization and Grande's approach are quite close to those obtained from the Runge–Kutta method. The dual criterion yields smaller errors than those of the remaining methods when the nonlinearity of the system increases, namely, when the heat capacity varies in the range [1.0, 3.0] × 10 4  J K −1 .

  17. Satellite single-axis attitude determination based on Automatic Dependent Surveillance - Broadcast signals

    Science.gov (United States)

    Zhou, Kaixing; Sun, Xiucong; Huang, Hai; Wang, Xinsheng; Ren, Guangwei

    2017-10-01

    The space-based Automatic Dependent Surveillance - Broadcast (ADS-B) is a new technology for air traffic management. The satellite equipped with spaceborne ADS-B system receives the broadcast signals from aircraft and transfers the message to ground stations, so as to extend the coverage area of terrestrial-based ADS-B. In this work, a novel satellite single-axis attitude determination solution based on the ADS-B receiving system is proposed. This solution utilizes the signal-to-noise ratio (SNR) measurement of the broadcast signals from aircraft to determine the boresight orientation of the ADS-B receiving antenna fixed on the satellite. The basic principle of this solution is described. The feasibility study of this new attitude determination solution is implemented, including the link budget and the access analysis. On this basis, the nonlinear least squares estimation based on the Levenberg-Marquardt method is applied to estimate the single-axis orientation. A full digital simulation has been carried out to verify the effectiveness and performance of this solution. Finally, the corresponding results are processed and presented minutely.

  18. CERES ERBE-like Instantaneous TOA Estimates (ES-8) in HDF (CER_ES8_TRMM-PFM_Edition2)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The ES-8 archival data product contains a 24-hour, single-satellite, instantaneous view of scanner fluxes at the top-of-atmosphere (TOA) reduced from spacecraft altitude unfiltered radiances using Earth Radiation Budget Experiment (ERBE) scanner Inversion algorithms and the ERBE shortwave (SW) and longwave (LW) Angular Distribution Models (ADMs). The ES-8 also includes the total (TOT), SW, LW, and window (WN) channel radiometric data; SW, LW, and WN unfiltered radiance values; and the ERBE scene identification for each measurement. These data are organized according to the CERES 3.3-second scan into 6.6-second records. As long as there is one valid scanner measurement within a record, the ES-8 record will be generated. The following CERES ES8 data sets are currently available: CER_ES8_TRMM-PFM_Edition1 CER_ES8_TRMM-PFM_Edition2 CER_ES8_TRMM-PFM_Transient-Ops2 CER_ES8_Terra-FM1_Edition1 CER_ES8_Terra-FM2_Edition1 CER_ES8_Terra-FM1_Edition2 CER_ES8_Terra-FM2_Edition2 CER_ES8_Aqua-FM3_Edition1 CER_ES8_Aqua-FM4_Edition1 CER_ES8_Aqua-FM3_Edition2 CER_ES8_Aqua-FM4_Edition2 CER_ES8_Aqua-FM3_Edition1-CV CER_ES8_Aqua-FM4_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1997-12-27; Stop_Date=2000-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 day; Temporal_Resolution_Range=Daily - < Weekly].

  19. MISR L2 TOA/Cloud Stereo Product subset for the ICARTT region V002

    Data.gov (United States)

    National Aeronautics and Space Administration — MISR Level 2 TOA/Cloud Stereo Product containing the Stereoscopically Derived Cloud Mask (SDCM), cloud winds, Reflecting Level Reference Altitude (RLRA), with...

  20. Indoor Navigation Test Results using an Integrated GPS/TOA/Inertial Navigation System

    National Research Council Canada - National Science Library

    Brown, Alison; Lu, Yan

    2006-01-01

    ...), wireless communications, and Time-of-Arrival (TOA) "Pseudolite" technology to provide location indoors for applications such as first responders, warfighters operating in urban terrain, and location-based services...

  1. Single event effect hardness for the front-end ASICs in the DAMPE satellite BGO calorimeter

    Science.gov (United States)

    Gao, Shan-Shan; Jiang, Di; Feng, Chang-Qing; Xi, Kai; Liu, Shu-Bin; An, Qi

    2016-01-01

    The Dark Matter Particle Explorer (DAMPE) is a Chinese scientific satellite designed for cosmic ray studies with a primary scientific goal of indirect detection of dark matter particles. As a crucial sub-detector, the BGO calorimeter measures the energy spectrum of cosmic rays in the energy range from 5 GeV to 10 TeV. In order to implement high-density front-end electronics (FEE) with the ability to measure 1848 signals from 616 photomultiplier tubes on the strictly constrained satellite platform, two kinds of 32-channel front-end ASICs, VA160 and VATA160, are customized. However, a space mission period of more than 3 years makes single event effects (SEEs) become threats to reliability. In order to evaluate SEE sensitivities of these chips and verify the effectiveness of mitigation methods, a series of laser-induced and heavy ion-induced SEE tests were performed. Benefiting from the single event latch-up (SEL) protection circuit for power supply, the triple module redundancy (TMR) technology for the configuration registers and the optimized sequential design for the data acquisition process, 52 VA160 chips and 32 VATA160 chips have been applied in the flight model of the BGO calorimeter with radiation hardness assurance. Supported by Strategic Priority Research Program on Space Science of the Chinese Academy of Sciences (XDA04040202-4) and Fundamental Research Funds for the Central Universities (WK2030040048)

  2. tavg1_2d_rad_Nx: MERRA 2D IAU Diagnostic, Radiation Surface and TOA, Time Average 1-hourly 0.667 x 0.5 degree V5.2.0 (MAT1NXRAD) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT1NXRAD or tavg1_2d_rad_Nx data product is the MERRA Data Assimilation System 2-Dimensional surface and TOA radiation flux that is time averaged single-level...

  3. Single Tree Vegetation Depth Estimation Tool for Satellite Services Link Design

    Directory of Open Access Journals (Sweden)

    Z. Hasirci

    2016-04-01

    Full Text Available Attenuation caused by tree shadowing is an important factor for describing the propagation channel of satellite services. Thus, vegetation effects should be determined by experimental studies or empirical formulations. In this study, tree types in the Black Sea Region of Turkey are classified based on their geometrical shapes into four groups such as conic, ellipsoid, spherical and hemispherical. The variations of the vegetation depth according to different tree shapes are calculated with ray tracing method. It is showed that different geometrical shapes have different vegetation depths even if they have same foliage volume for different elevation angles. The proposed method is validated with the related literature in terms of average single tree attenuation. On the other hand, due to decrease system requirements (speed, memory usage etc. of ray tracing method, an artificial neural network is proposed as an alternative. A graphical user interface is created for the above processes in MATLAB environment named vegetation depth estimation tool (VdET.

  4. A Minimum Variance Algorithm for Overdetermined TOA Equations with an Altitude Constraint.

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Louis A; Mason, John J.

    2018-04-01

    We present a direct (non-iterative) method for solving for the location of a radio frequency (RF) emitter, or an RF navigation receiver, using four or more time of arrival (TOA) measurements and an assumed altitude above an ellipsoidal earth. Both the emitter tracking problem and the navigation application are governed by the same equations, but with slightly different interpreta- tions of several variables. We treat the assumed altitude as a soft constraint, with a specified noise level, just as the TOA measurements are handled, with their respective noise levels. With 4 or more TOA measurements and the assumed altitude, the problem is overdetermined and is solved in the weighted least squares sense for the 4 unknowns, the 3-dimensional position and time. We call the new technique the TAQMV (TOA Altitude Quartic Minimum Variance) algorithm, and it achieves the minimum possible error variance for given levels of TOA and altitude estimate noise. The method algebraically produces four solutions, the least-squares solution, and potentially three other low residual solutions, if they exist. In the lightly overdermined cases where multiple local minima in the residual error surface are more likely to occur, this algebraic approach can produce all of the minima even when an iterative approach fails to converge. Algorithm performance in terms of solution error variance and divergence rate for bas eline (iterative) and proposed approach are given in tables.

  5. CERES Monthly Gridded Single Satellite Fluxes and Clouds (FSW) in HDF (CER_FSW_TRMM-PFM-VIRS_Beta1)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator)

    The Monthly Gridded Radiative Fluxes and Clouds (FSW) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The FSW is also produced for combinations of scanner instruments. All instantaneous fluxes from the CERES CRS product for a month are sorted by 1-degree spatial regions and by the Universal Time (UT) hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the FSW along with other flux statistics and scene information. The mean adjusted fluxes at the four atmospheric levels defined by CRS are also included for both clear-sky and total-sky scenes. In addition, four cloud height categories are defined by dividing the atmosphere into four intervals with boundaries at the surface, 700-, 500-, 300-hPa, and the Top-of-the-Atmosphere (TOA). The cloud layers from CRS are put into one of the cloud height categories and averaged over the region. The cloud properties are also column averaged and included on the FSW. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2000-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

  6. The effect of organic water-miscible solvents on the extraction of uranium by TOA

    International Nuclear Information System (INIS)

    Shi Xiukun; Shen Xinghai; Pen Qixiu; Gao Hongchen

    1989-01-01

    The effect of organic water-miscible solvents, such as methanol, ethanol, acetone, dioxane, glycol, dimethylsulfoxide (DMSO), dimethylformamide (DMF), tetrahydrofurance (THF) in aqueous phase on the extraction of uranyl sulphate by tri-n-octylamine (TOA) has been investigated. All data obtained showed that the addition of alcohols, ketones etc. into aqueous phase brings about an increase of distribution ratio of uranium, whereas the addition of DMSO, DMF etc. brings about a decrease of distribution ratio of uranium. In the present study, the regularity and mechanism of extraction with TOA are further studied and discussed from the measurements of some physical properties, such as dielectric constant, interface tension etc

  7. Radiative effect differences between multi-layered and single-layer clouds derived from CERES, CALIPSO, and CloudSat data

    International Nuclear Information System (INIS)

    Li Jiming; Yi Yuhong; Minnis, Patrick; Huang Jianping; Yan Hongru; Ma Yuejie; Wang Wencai; Kirk Ayers, J.

    2011-01-01

    Clouds alter general circulation through modification of the radiative heating profile within the atmosphere. Their effects are complex and depend on height, vertical structure, and phase. The instantaneous cloud radiative effect (CRE) induced by multi-layered (ML) and single-layer (SL) clouds is estimated by analyzing data collected by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, and Clouds and Earth's Radiation Energy Budget System (CERES) missions from March 2007 through February 2008. The CRE differences between ML and SL clouds at the top of the atmosphere (TOA) and at the surface were also examined. The zonal mean shortwave (SW) CRE differences between the ML and SL clouds at the TOA and surface were positive at most latitudes, peaking at 120 W m -2 in the tropics and dropping to -30 W m -2 at higher latitudes. This indicated that the ML clouds usually reflected less sunlight at the TOA and transmitted more to the surface than the SL clouds, due to their higher cloud top heights. The zonal mean longwave (LW) CRE differences between ML and SL clouds at the TOA and surface were relatively small, ranging from -30 to 30 W m -2 . This showed that the ML clouds only increased the amount of thermal radiation at the TOA relative to the SL clouds in the tropics, decreasing it elsewhere. In other words, ML clouds tended to cool the atmosphere in the tropics and warm it elsewhere when compared to SL clouds. The zonal mean net CRE differences were positive at most latitudes and dominated by the SW CRE differences.

  8. Adsorption properties of technetium and rhenium for hybrid microcapsules enclosing Toa extractant

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.; Mimura, H.; Niibori, Y. [Tohoku University, Graduate School of Engineering, Department of Quantum Science and Energy Engineering, Aramaki-Aza-Aoba 6-6-01-2, Aoba-ku, Sendai-shi, Miyagi-ken, 980-8579 Japan (Japan); Koyama, S.; Ohnishi, T., E-mail: yanwu@cyric.tohoku.ac.j [Japan Atomic Energy Agency, O-arai Research and Development Center, Fuels and Materials Department, Alpha-Gamma Section, Narita-cho 4002, O-arai-machi, Ibaraki, 311-1393 Japan (Japan)

    2010-10-15

    Special attention has been given to the separation and recovery of the VII-group elements Tc and Re, in relation to the partitioning of high-level liquid waste (HLLW) generated from the nuclear fuel reprocessing process. In this study, a tertiary amine (tri-n-octylamine Toa), which is effective for the extraction of oxo anions, was encapsulated in a calcium alginate gel polymer (CaALG), and the adsorption behaviours of TcO{sub 4} and ReO{sub 4}{sup -} in the presence of nitric acid and hydrochloric acid were examined by using calcium alginate microcapsules (M Cs) enclosing Toa extractant (Toa-CaALG M Cs). The order of the distribution coefficient K{sub d} for different oxo anions at 0.1 M HNO{sub 3} was ReO{sub 4}{sup -}> WO{sub 4}{sup 2-}> CrO{sub 4}{sup 2-} {approx} MoO{sub 4}{sup 2-}>> SeO{sub 3}{sup 2-}. Toa-CaALG still exhibited high uptake ability for ReO{sub 4}{sup -} even after irradiation with {sup 60}Co {gamma}-rays (dose: 17.6 kGy). Uptake of TcO{sub 4}{sup -} in the presence of 1 M HNO{sub 3} was readily attained within 3 h. Relatively large K{sub d} values above 10{sup 2} cm{sup 3}/g were obtained for Toa-CaALG in the presence of 0.01 {approx} 1 M HNO{sub 3}. All of the TcO{sub 4}{sup -} was successfully adsorbed by Toa-CaALG from the simulated HLLW. The adsorbed TcO{sub 4}{sup -} was then effectively eluted with 5 M or 7 M HNO{sub 3} solution. Further, the selective uptake of ReO{sub 4}{sup -} (a chemical analogue of TcO{sub 4}{sup -}) was confirmed by using actual HLLW (Fbr, Joyo, JAEA), and uptake (%) above 99% was obtained. Toa-CaALG was thus effective for the selective separation and recovery of TcO{sub 4}{sup -} and ReO{sub 4}{sup -} from waste solutions containing highly concentrated HNO{sub 3} and NaNO{sub 3}. Microencapsulation techniques with alginate gel polymer can be applied to other ion exchangers and extractants, and the M Cs immobilizing these adsorbents are effective for the advanced separation of various radionuclides, rare metals and

  9. Statistical properties of single-mode fiber coupling of satellite-to-ground laser links partially corrected by adaptive optics.

    Science.gov (United States)

    Canuet, Lucien; Védrenne, Nicolas; Conan, Jean-Marc; Petit, Cyril; Artaud, Geraldine; Rissons, Angelique; Lacan, Jerome

    2018-01-01

    In the framework of satellite-to-ground laser downlinks, an analytical model describing the variations of the instantaneous coupled flux into a single-mode fiber after correction of the incoming wavefront by partial adaptive optics (AO) is presented. Expressions for the probability density function and the cumulative distribution function as well as for the average fading duration and fading duration distribution of the corrected coupled flux are given. These results are of prime interest for the computation of metrics related to coded transmissions over correlated channels, and they are confronted by end-to-end wave-optics simulations in the case of a geosynchronous satellite (GEO)-to-ground and a low earth orbit satellite (LEO)-to-ground scenario. Eventually, the impact of different AO performances on the aforementioned fading duration distribution is analytically investigated for both scenarios.

  10. Spin motion determination of the Envisat satellite through laser ranging measurements from a single pass measured by a single station

    Science.gov (United States)

    Pittet, Jean-Noël; Šilha, Jiří; Schildknecht, Thomas

    2018-02-01

    The Satellite Laser Ranging (SLR) technology is used to accurately determine the position of space objects equipped with so-called retro-reflectors or retro-reflector arrays (RRA). This type of measurement allows to measure the range to the spacecraft with high precision, which leads to determination of very accurate orbits for these targets. Non-active spacecraft, which are not attitude controlled any longer, tend to start to spin or tumble under influence of the external and internal torques and forces. If the return signal is measured for a non-spherical non-active rotating object, the signal in the range residuals with respect to the reference orbit is more complex. For rotating objects the return signal shows an oscillating pattern or patterns caused by the RRA moving around the satellite's centre of mass. This behaviour is projected onto the radial component measured by the SLR. In our work, we demonstrate how the SLR ranging technique from one sensor to a satellite equipped with a RRA can be used to precisely determine its spin motion during one passage. Multiple SLR measurements of one target over time allow to accurately monitor spin motion changes which can be further used for attitude predictions. We show our solutions of the spin motion determined for the non-active ESA satellite Envisat obtained from measurements acquired during years 2013-2015 by the Zimmerwald SLR station, Switzerland. All the necessary parameters are defined for our own so-called point-like model which describes the motion of a point in space around the satellite centre of mass.

  11. CERES ERBE-like Instantaneous TOA Estimates (ES-8) in HDF (CER_ES8_Aqua-FM4_Edition1-CV)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The ES-8 archival data product contains a 24-hour, single-satellite, instantaneous view of scanner fluxes at the top-of-atmosphere (TOA) reduced from spacecraft altitude unfiltered radiances using Earth Radiation Budget Experiment (ERBE) scanner Inversion algorithms and the ERBE shortwave (SW) and longwave (LW) Angular Distribution Models (ADMs). The ES-8 also includes the total (TOT), SW, LW, and window (WN) channel radiometric data; SW, LW, and WN unfiltered radiance values; and the ERBE scene identification for each measurement. These data are organized according to the CERES 3.3-second scan into 6.6-second records. As long as there is one valid scanner measurement within a record, the ES-8 record will be generated. The following CERES ES8 data sets are currently available: CER_ES8_TRMM-PFM_Edition1 CER_ES8_TRMM-PFM_Edition2 CER_ES8_TRMM-PFM_Transient-Ops2 CER_ES8_Terra-FM1_Edition1 CER_ES8_Terra-FM2_Edition1 CER_ES8_Terra-FM1_Edition2 CER_ES8_Terra-FM2_Edition2 CER_ES8_Aqua-FM3_Edition1 CER_ES8_Aqua-FM4_Edition1 CER_ES8_Aqua-FM3_Edition2 CER_ES8_Aqua-FM4_Edition2 CER_ES8_Aqua-FM3_Edition1-CV CER_ES8_Aqua-FM4_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1997-12-27; Stop_Date=2005-03-29] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 day; Temporal_Resolution_Range=Daily - < Weekly].

  12. CERES ERBE-like Instantaneous TOA Estimates (ES-8) in HDF (CER_ES8_Terra-FM1_Edition2)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The ES-8 archival data product contains a 24-hour, single-satellite, instantaneous view of scanner fluxes at the top-of-atmosphere (TOA) reduced from spacecraft altitude unfiltered radiances using Earth Radiation Budget Experiment (ERBE) scanner Inversion algorithms and the ERBE shortwave (SW) and longwave (LW) Angular Distribution Models (ADMs). The ES-8 also includes the total (TOT), SW, LW, and window (WN) channel radiometric data; SW, LW, and WN unfiltered radiance values; and the ERBE scene identification for each measurement. These data are organized according to the CERES 3.3-second scan into 6.6-second records. As long as there is one valid scanner measurement within a record, the ES-8 record will be generated. The following CERES ES8 data sets are currently available: CER_ES8_TRMM-PFM_Edition1 CER_ES8_TRMM-PFM_Edition2 CER_ES8_TRMM-PFM_Transient-Ops2 CER_ES8_Terra-FM1_Edition1 CER_ES8_Terra-FM2_Edition1 CER_ES8_Terra-FM1_Edition2 CER_ES8_Terra-FM2_Edition2 CER_ES8_Aqua-FM3_Edition1 CER_ES8_Aqua-FM4_Edition1 CER_ES8_Aqua-FM3_Edition2 CER_ES8_Aqua-FM4_Edition2 CER_ES8_Aqua-FM3_Edition1-CV CER_ES8_Aqua-FM4_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1997-12-27; Stop_Date=2006-01-01] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 day; Temporal_Resolution_Range=Daily - < Weekly].

  13. CERES ERBE-like Instantaneous TOA Estimates (ES-8) in HDF (CER_ES8_Terra-FM1_Edition1-CV)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The ES-8 archival data product contains a 24-hour, single-satellite, instantaneous view of scanner fluxes at the top-of-atmosphere (TOA) reduced from spacecraft altitude unfiltered radiances using Earth Radiation Budget Experiment (ERBE) scanner Inversion algorithms and the ERBE shortwave (SW) and longwave (LW) Angular Distribution Models (ADMs). The ES-8 also includes the total (TOT), SW, LW, and window (WN) channel radiometric data; SW, LW, and WN unfiltered radiance values; and the ERBE scene identification for each measurement. These data are organized according to the CERES 3.3-second scan into 6.6-second records. As long as there is one valid scanner measurement within a record, the ES-8 record will be generated. The following CERES ES8 data sets are currently available: CER_ES8_TRMM-PFM_Edition1 CER_ES8_TRMM-PFM_Edition2 CER_ES8_TRMM-PFM_Transient-Ops2 CER_ES8_Terra-FM1_Edition1 CER_ES8_Terra-FM2_Edition1 CER_ES8_Terra-FM1_Edition2 CER_ES8_Terra-FM2_Edition2 CER_ES8_Aqua-FM3_Edition1 CER_ES8_Aqua-FM4_Edition1 CER_ES8_Aqua-FM3_Edition2 CER_ES8_Aqua-FM4_Edition2 CER_ES8_Aqua-FM3_Edition1-CV CER_ES8_Aqua-FM4_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1997-12-27; Stop_Date=2006-09-30] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 day; Temporal_Resolution_Range=Daily - < Weekly].

  14. CERES ERBE-like Instantaneous TOA Estimates (ES-8) in HDF (CER_ES8_Terra-FM2_Edition1)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The ES-8 archival data product contains a 24-hour, single-satellite, instantaneous view of scanner fluxes at the top-of-atmosphere (TOA) reduced from spacecraft altitude unfiltered radiances using Earth Radiation Budget Experiment (ERBE) scanner Inversion algorithms and the ERBE shortwave (SW) and longwave (LW) Angular Distribution Models (ADMs). The ES-8 also includes the total (TOT), SW, LW, and window (WN) channel radiometric data; SW, LW, and WN unfiltered radiance values; and the ERBE scene identification for each measurement. These data are organized according to the CERES 3.3-second scan into 6.6-second records. As long as there is one valid scanner measurement within a record, the ES-8 record will be generated. The following CERES ES8 data sets are currently available: CER_ES8_TRMM-PFM_Edition1 CER_ES8_TRMM-PFM_Edition2 CER_ES8_TRMM-PFM_Transient-Ops2 CER_ES8_Terra-FM1_Edition1 CER_ES8_Terra-FM2_Edition1 CER_ES8_Terra-FM1_Edition2 CER_ES8_Terra-FM2_Edition2 CER_ES8_Aqua-FM3_Edition1 CER_ES8_Aqua-FM4_Edition1 CER_ES8_Aqua-FM3_Edition2 CER_ES8_Aqua-FM4_Edition2 CER_ES8_Aqua-FM3_Edition1-CV CER_ES8_Aqua-FM4_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1997-12-27; Stop_Date=2005-11-01] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 day; Temporal_Resolution_Range=Daily - < Weekly].

  15. CERES ERBE-like Instantaneous TOA Estimates (ES-8) in HDF (CER_ES8_Aqua-FM3_Edition2)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The ES-8 archival data product contains a 24-hour, single-satellite, instantaneous view of scanner fluxes at the top-of-atmosphere (TOA) reduced from spacecraft altitude unfiltered radiances using Earth Radiation Budget Experiment (ERBE) scanner Inversion algorithms and the ERBE shortwave (SW) and longwave (LW) Angular Distribution Models (ADMs). The ES-8 also includes the total (TOT), SW, LW, and window (WN) channel radiometric data; SW, LW, and WN unfiltered radiance values; and the ERBE scene identification for each measurement. These data are organized according to the CERES 3.3-second scan into 6.6-second records. As long as there is one valid scanner measurement within a record, the ES-8 record will be generated. The following CERES ES8 data sets are currently available: CER_ES8_TRMM-PFM_Edition1 CER_ES8_TRMM-PFM_Edition2 CER_ES8_TRMM-PFM_Transient-Ops2 CER_ES8_Terra-FM1_Edition1 CER_ES8_Terra-FM2_Edition1 CER_ES8_Terra-FM1_Edition2 CER_ES8_Terra-FM2_Edition2 CER_ES8_Aqua-FM3_Edition1 CER_ES8_Aqua-FM4_Edition1 CER_ES8_Aqua-FM3_Edition2 CER_ES8_Aqua-FM4_Edition2 CER_ES8_Aqua-FM3_Edition1-CV CER_ES8_Aqua-FM4_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV CER_ES8_Terra-FM1_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1997-12-27; Stop_Date=2005-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Temporal_Resolution=1 day; Temporal_Resolution_Range=Daily - < Weekly].

  16. Fingerprinting Localization Method Based on TOA and Particle Filtering for Mines

    Directory of Open Access Journals (Sweden)

    Boming Song

    2017-01-01

    Full Text Available Accurate target localization technology plays a very important role in ensuring mine safety production and higher production efficiency. The localization accuracy of a mine localization system is influenced by many factors. The most significant factor is the non-line of sight (NLOS propagation error of the localization signal between the access point (AP and the target node (Tag. In order to improve positioning accuracy, the NLOS error must be suppressed by an optimization algorithm. However, the traditional optimization algorithms are complex and exhibit poor optimization performance. To solve this problem, this paper proposes a new method for mine time of arrival (TOA localization based on the idea of comprehensive optimization. The proposed method utilizes particle filtering to reduce the TOA data error, and the positioning results are further optimized with fingerprinting based on the Manhattan distance. This proposed method combines the advantages of particle filtering and fingerprinting localization. It reduces algorithm complexity and has better error suppression performance. The experimental results demonstrate that, as compared to the symmetric double-sided two-way ranging (SDS-TWR method or received signal strength indication (RSSI based fingerprinting method, the proposed method has a significantly improved localization performance, and the environment adaptability is enhanced.

  17. Preparation and Characterisation of tri-n-octylamine Microcapsule (TOA-MC) as Selective Separation of Re (VII)

    International Nuclear Information System (INIS)

    Tsai, T.L.; Mimura, H.; Syed, M.R.; Yin, X.B.; Lee, C.P.; Tsai, S.C.

    2015-01-01

    Much attention has been paid on the selective separation and effective utilisation of 99 Tc from high level radioactive liquid waste (HLLW). TOA-MC was developed as an absorbent for Re (VII), a substitute for Tc (VII) due to their similarities of chemical behaviour in this study. The uptake (%), normally above 95% of Re (VII) for TOA-MC in the presence of dilute HNO 3 (0.01∼0.1 M) was strongly retained and decreased with higher HNO 3 concentration by batch method. The surface morphology and thermal stability of microcapsules were characterised by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), respectively. The diameters in the range of 700-800 μm and size distribution of the microcapsules were examined using digital microscope (DM). The chemical structures of the synthesised microcapsules and two starting materials of TOA and sodium alginate (NaALG) were performed using Fourier transform infrared spectroscopy (FTIR). (authors)

  18. [Application of single-band brightness variance ratio to the interference dissociation of cloud for satellite data].

    Science.gov (United States)

    Qu, Wei-ping; Liu, Wen-qing; Liu, Jian-guo; Lu, Yi-huai; Zhu, Jun; Qin, Min; Liu, Cheng

    2006-11-01

    In satellite remote-sensing detection, cloud as an interference plays a negative role in data retrieval. How to discern the cloud fields with high fidelity thus comes as a need to the following research. A new method rooting in atmospheric radiation characteristics of cloud layer, in the present paper, presents a sort of solution where single-band brightness variance ratio is used to detect the relative intensity of cloud clutter so as to delineate cloud field rapidly and exactly, and the formulae of brightness variance ratio of satellite image, image reflectance variance ratio, and brightness temperature variance ratio of thermal infrared image are also given to enable cloud elimination to produce data free from cloud interference. According to the variance of the penetrating capability for different spectra bands, an objective evaluation is done on cloud penetration of them with the factors that influence penetration effect. Finally, a multi-band data fusion task is completed using the image data of infrared penetration from cirrus nothus. Image data reconstruction is of good quality and exactitude to show the real data of visible band covered by cloud fields. Statistics indicates the consistency of waveband relativity with image data after the data fusion.

  19. Sea ice local surface topography from single-pass satellite InSAR measurements: a feasibility study

    Directory of Open Access Journals (Sweden)

    W. Dierking

    2017-08-01

    Full Text Available Quantitative parameters characterizing the sea ice surface topography are needed in geophysical investigations such as studies on atmosphere–ice interactions or sea ice mechanics. Recently, the use of space-borne single-pass interferometric synthetic aperture radar (InSAR for retrieving the ice surface topography has attracted notice among geophysicists. In this paper the potential of InSAR measurements is examined for several satellite configurations and radar frequencies, considering statistics of heights and widths of ice ridges as well as possible magnitudes of ice drift. It is shown that, theoretically, surface height variations can be retrieved with relative errors  ≤  0.5 m. In practice, however, the sea ice drift and open water leads may contribute significantly to the measured interferometric phase. Another essential factor is the dependence of the achievable interferometric baseline on the satellite orbit configurations. Possibilities to assess the influence of different factors on the measurement accuracy are demonstrated: signal-to-noise ratio, presence of a snow layer, and the penetration depth into the ice. Practical examples of sea surface height retrievals from bistatic SAR images collected during the TanDEM-X Science Phase are presented.

  20. Preparation and characterization of a sulindac sensor based on PVC/TOA-SUL membrane.

    Science.gov (United States)

    Lenik, Joanna

    2014-04-01

    A potentiometric sulindac sensitive sensor based on tetraoctylammonium (Z)-5-fluoro-2-methyl-1-[[p-(methylsulfinyl)phenyl]methylene]-1H-indene-3-acetate (TOA-SUL) was described. The electrode responded with sensitivity of 57.5±1.6mV decade(-1) over the linear range 5×10(-5)-1×10(-2)mol L(-1) at pH6.0-9.0. It had the limit of detection 1.4×10(-5)mol L(-1), a fast response time of 13s and showed clear discrimination of sulindac ions from several inorganic and organic compounds and also amino acids. This electrode did not contain any inner solutions, so it was easy and comfortable to use. The proposed sensor was used to determine sulindac in clear solution and in urine sample solution. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. CERES Monthly Gridded Single Satellite Fluxes and Clouds (FSW) in HDF (CER_FSW_Terra-FM1-MODIS_Edition2C)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator)

    The Monthly Gridded Radiative Fluxes and Clouds (FSW) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The FSW is also produced for combinations of scanner instruments. All instantaneous fluxes from the CERES CRS product for a month are sorted by 1-degree spatial regions and by the Universal Time (UT) hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the FSW along with other flux statistics and scene information. The mean adjusted fluxes at the four atmospheric levels defined by CRS are also included for both clear-sky and total-sky scenes. In addition, four cloud height categories are defined by dividing the atmosphere into four intervals with boundaries at the surface, 700-, 500-, 300-hPa, and the Top-of-the-Atmosphere (TOA). The cloud layers from CRS are put into one of the cloud height categories and averaged over the region. The cloud properties are also column averaged and included on the FSW. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

  2. CERES) Monthly Gridded Single Satellite Fluxes and Clouds (FSW) in HDF (CER_FSW_Terra-FM2-MODIS_Edition2C)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator)

    The Monthly Gridded Radiative Fluxes and Clouds (FSW) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The FSW is also produced for combinations of scanner instruments. All instantaneous fluxes from the CERES CRS product for a month are sorted by 1-degree spatial regions and by the Universal Time (UT) hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the FSW along with other flux statistics and scene information. The mean adjusted fluxes at the four atmospheric levels defined by CRS are also included for both clear-sky and total-sky scenes. In addition, four cloud height categories are defined by dividing the atmosphere into four intervals with boundaries at the surface, 700-, 500-, 300-hPa, and the Top-of-the-Atmosphere (TOA). The cloud layers from CRS are put into one of the cloud height categories and averaged over the region. The cloud properties are also column averaged and included on the FSW. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2001-10-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

  3. 78 FR 20887 - Approval of Subzone Status; Pepsi Cola Puerto Rico Distributing, LLC, Toa Baja, Puerto Rico

    Science.gov (United States)

    2013-04-08

    ... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [S-132-2012] Approval of Subzone Status; Pepsi Cola Puerto Rico Distributing, LLC, Toa Baja, Puerto Rico On December 7, 2012, the Executive Secretary... activation limit of FTZ 7, on [[Page 20888

  4. The skeletal muscle satellite cell response to a single bout of resistance-type exercise is delayed with aging in men

    NARCIS (Netherlands)

    Snijders, T.; Verdijk, L.B.; Smeets, J.S.J.; McKay, B.R.; Senden, J.M.G.; Hartgens, F.; Parise, G.; Greenhaff, P.; van Loon, L.J.C.

    2014-01-01

    Skeletal muscle satellite cells (SCs) have been shown to be instrumental in the muscle adaptive response to exercise. The present study determines age-related differences in SC content and activation status following a single bout of exercise. Ten young (22 +/- 1 years) and 10 elderly (73 +/- 1

  5. Modeling satellite-Earth quantum channel downlinks with adaptive-optics coupling to single-mode fibers

    Science.gov (United States)

    Gruneisen, Mark T.; Flanagan, Michael B.; Sickmiller, Brett A.

    2017-12-01

    The efficient coupling of photons from a free-space quantum channel into a single-mode optical fiber (SMF) has important implications for quantum network concepts involving SMF interfaces to quantum detectors, atomic systems, integrated photonics, and direct coupling to a fiber network. Propagation through atmospheric turbulence, however, leads to wavefront errors that degrade mode matching with SMFs. In a free-space quantum channel, this leads to photon losses in proportion to the severity of the aberration. This is particularly problematic for satellite-Earth quantum channels, where atmospheric turbulence can lead to significant wavefront errors. This report considers propagation from low-Earth orbit to a terrestrial ground station and evaluates the efficiency with which photons couple either through a circular field stop or into an SMF situated in the focal plane of the optical receiver. The effects of atmospheric turbulence on the quantum channel are calculated numerically and quantified through the quantum bit error rate and secure key generation rates in a decoy-state BB84 protocol. Numerical simulations include the statistical nature of Kolmogorov turbulence, sky radiance, and an adaptive-optics system under closed-loop control.

  6. Research on Modeling of the Agile Satellite Using a Single Gimbal Magnetically Suspended CMG and the Disturbance Feedforward Compensation for Rotors

    Science.gov (United States)

    Cui, Peiling; Yan, Ning

    2012-01-01

    The magnetically suspended Control Moment Gyroscope (CMG) has the advantages of long-life, micro-vibration and being non-lubricating, and is the ideal actuator for agile maneuver satellite attitude control. However, the stability of the rotor in magnetic bearing and the precision of the output torque of a magnetically suspended CMG are affected by the rapid maneuvers of satellites. In this paper, a dynamic model of the agile satellite including a magnetically suspended single gimbal control moment gyroscope is built and the equivalent disturbance torque effected on the rotor is obtained. The feedforward compensation control method is used to depress the disturbance on the rotor. Simulation results are given to show that the rotor displacement is obviously reduced. PMID:23235442

  7. Research on Modeling of the Agile Satellite Using a Single Gimbal Magnetically Suspended CMG and the Disturbance Feedforward Compensation for Rotors

    Directory of Open Access Journals (Sweden)

    Ning Yan

    2012-12-01

    Full Text Available The magnetically suspended Control Moment Gyroscope (CMG has the advantages of long-life, micro-vibration and being non-lubricating, and is the ideal actuator for agile maneuver satellite attitude control. However, the stability of the rotor in magnetic bearing and the precision of the output torque of a magnetically suspended CMG are affected by the rapid maneuvers of satellites. In this paper, a dynamic model of the agile satellite including a magnetically suspended single gimbal control moment gyroscope is built and the equivalent disturbance torque effected on the rotor is obtained. The feedforward compensation control method is used to depress the disturbance on the rotor. Simulation results are given to show that the rotor displacement is obviously reduced.

  8. The Influence of Extractant TOA, Stirring Time on the Extraction ProcessLiquid-liquid, and Liquid Membrane on the Liquid Wastes Containing Cd

    International Nuclear Information System (INIS)

    Prayitno; Djoko-Sardjono; Nurimaniwati; Adhe-Helmayani

    2000-01-01

    The influence of extractant and stirring time on the reduction componentcadmium on liquid wastes has been investigated. The method of experimentalused the extraction with liquid membrane emulsion. The parameters to beinvestigated were extractant amount tri-n octylamine (TOA), duration ofstirring time. In this investigated, extractant amount was varied from 5 to25 % (v/v) TOA, duration of stirring time varied from 5 to minutes. Theresult of experimental can be concluded that the best condition obtained forreducing cadmium component was on extractant amount 20 % (v/v) TOA, stirringtime 25 minutes. The best condition for reducing the cadmium component wasefficiency factor 98.35%. (author)

  9. Rayleigh radiance computations for satellite remote sensing: accounting for the effect of sensor spectral response function.

    Science.gov (United States)

    Wang, Menghua

    2016-05-30

    To understand and assess the effect of the sensor spectral response function (SRF) on the accuracy of the top of the atmosphere (TOA) Rayleigh-scattering radiance computation, new TOA Rayleigh radiance lookup tables (LUTs) over global oceans and inland waters have been generated. The new Rayleigh LUTs include spectral coverage of 335-2555 nm, all possible solar-sensor geometries, and surface wind speeds of 0-30 m/s. Using the new Rayleigh LUTs, the sensor SRF effect on the accuracy of the TOA Rayleigh radiance computation has been evaluated for spectral bands of the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (SNPP) satellite and the Joint Polar Satellite System (JPSS)-1, showing some important uncertainties for VIIRS-SNPP particularly for large solar- and/or sensor-zenith angles as well as for large Rayleigh optical thicknesses (i.e., short wavelengths) and bands with broad spectral bandwidths. To accurately account for the sensor SRF effect, a new correction algorithm has been developed for VIIRS spectral bands, which improves the TOA Rayleigh radiance accuracy to ~0.01% even for the large solar-zenith angles of 70°-80°, compared with the error of ~0.7% without applying the correction for the VIIRS-SNPP 410 nm band. The same methodology that accounts for the sensor SRF effect on the Rayleigh radiance computation can be used for other satellite sensors. In addition, with the new Rayleigh LUTs, the effect of surface atmospheric pressure variation on the TOA Rayleigh radiance computation can be calculated precisely, and no specific atmospheric pressure correction algorithm is needed. There are some other important applications and advantages to using the new Rayleigh LUTs for satellite remote sensing, including an efficient and accurate TOA Rayleigh radiance computation for hyperspectral satellite remote sensing, detector-based TOA Rayleigh radiance computation, Rayleigh radiance calculations for high altitude

  10. Stripping voltammetry of technetium using a TOA modified carbon paste electrode

    International Nuclear Information System (INIS)

    Ruf, H.; Schorb, K.

    1989-10-01

    Low concentrations of technetium have been measured DP-stripping-voltammetrically using a carbon paste electrode modified with tri-n-octylamine (TOA-CPE). Preconcentration of the metal ion on the electrode surface accomplished by dipping of the latter in the sample solution which is 2M in HCl, relies on the chemical reaction with the amine acting as a liquid anion exchanger. Both, Tc-IV occurring as the TcCl 6 2- ion in chloride solutions as well as Tc-VII hereby are deposited. Measurements following deposition yield voltammograms of essentially different shapes for the two Tc species. With Tc-IV a characteristic curve with a prominent current signal at -280 mV (vs. Ag/AgCl) is obtained which can be evaluated for Tc quantitation. However, starting from Tc-VII, complex voltammograms are registered not allowing direct technetium assays. Nevertheless, after reduction to Tc-IV, e.g. by means of ascorbic acid, also Tc-VII can be quantified reliably by the method described, the lower detection limit for both oxidation states being about 4x10 -8 M. (orig.) [de

  11. A TOA-AOA-Based NLOS Error Mitigation Method for Location Estimation

    Directory of Open Access Journals (Sweden)

    Tianshuang Qiu

    2007-12-01

    Full Text Available This paper proposes a geometric method to locate a mobile station (MS in a mobile cellular network when both the range and angle measurements are corrupted by non-line-of-sight (NLOS errors. The MS location is restricted to an enclosed region by geometric constraints from the temporal-spatial characteristics of the radio propagation channel. A closed-form equation of the MS position, time of arrival (TOA, angle of arrival (AOA, and angle spread is provided. The solution space of the equation is very large because the angle spreads are random variables in nature. A constrained objective function is constructed to further limit the MS position. A Lagrange multiplier-based solution and a numerical solution are proposed to resolve the MS position. The estimation quality of the estimator in term of “biased” or “unbiased” is discussed. The scale factors, which may be used to evaluate NLOS propagation level, can be estimated by the proposed method. AOA seen at base stations may be corrected to some degree. The performance comparisons among the proposed method and other hybrid location methods are investigated on different NLOS error models and with two scenarios of cell layout. It is found that the proposed method can deal with NLOS error effectively, and it is attractive for location estimation in cellular networks.

  12. Effect of n-octanol on the extraction behavior of trace cobalt in TOA-HCl system

    International Nuclear Information System (INIS)

    Mukhopadhyay, Krishnendu; Mandal, Anjana; Mukhopadhyay, Banani; Nayak, Dalia; Lahiri, Susanta

    1997-01-01

    Effect of the presence of n-octanol in the extraction of traces of cobalt in HCl-TOA system was studied. In the extraction, both synergistic and antagonistic effects, depending on the volume of alcohol present, were observed. Extraction behaviour of the element was studied radiometrically using 57,58 Co, produced by α- particle bombardment of cobalt, as radiotracer for the element. (author). 1 fig

  13. Scale dependence of cirrus horizontal heterogeneity effects on TOA measurements – Part I: MODIS brightness temperatures in the thermal infrared

    Directory of Open Access Journals (Sweden)

    T. Fauchez

    2017-07-01

    Full Text Available This paper presents a study on the impact of cirrus cloud heterogeneities on MODIS simulated thermal infrared (TIR brightness temperatures (BTs at the top of the atmosphere (TOA as a function of spatial resolution from 50 m to 10 km. A realistic 3-D cirrus field is generated by the 3DCLOUD model (average optical thickness of 1.4, cloud-top and base altitudes at 10 and 12 km, respectively, consisting of aggregate column crystals of Deff = 20 µm, and 3-D thermal infrared radiative transfer (RT is simulated with the 3DMCPOL code. According to previous studies, differences between 3-D BT computed from a heterogenous pixel and 1-D RT computed from a homogeneous pixel are considered dependent at nadir on two effects: (i the optical thickness horizontal heterogeneity leading to the plane-parallel homogeneous bias (PPHB and the (ii horizontal radiative transport (HRT leading to the independent pixel approximation error (IPAE. A single but realistic cirrus case is simulated and, as expected, the PPHB mainly impacts the low-spatial-resolution results (above ∼ 250 m with averaged values of up to 5–7 K, while the IPAE mainly impacts the high-spatial-resolution results (below ∼ 250 m with average values of up to 1–2 K. A sensitivity study has been performed in order to extend these results to various cirrus optical thicknesses and heterogeneities by sampling the cirrus in several ranges of parameters. For four optical thickness classes and four optical heterogeneity classes, we have found that, for nadir observations, the spatial resolution at which the combination of PPHB and HRT effects is the smallest, falls between 100 and 250 m. These spatial resolutions thus appear to be the best choice to retrieve cirrus optical properties with the smallest cloud heterogeneity-related total bias in the thermal infrared. For off-nadir observations, the average total effect is increased and the minimum is shifted to coarser spatial

  14. Novel joint TOA/RSSI-based WCE location tracking method without prior knowledge of biological human body tissues.

    Science.gov (United States)

    Ito, Takahiro; Anzai, Daisuke; Jianqing Wang

    2014-01-01

    This paper proposes a novel joint time of arrival (TOA)/received signal strength indicator (RSSI)-based wireless capsule endoscope (WCE) location tracking method without prior knowledge of biological human tissues. Generally, TOA-based localization can achieve much higher localization accuracy than other radio frequency-based localization techniques, whereas wireless signals transmitted from a WCE pass through various kinds of human body tissues, as a result, the propagation velocity inside a human body should be different from one in free space. Because the variation of propagation velocity is mainly affected by the relative permittivity of human body tissues, instead of pre-measurement for the relative permittivity in advance, we simultaneously estimate not only the WCE location but also the relative permittivity information. For this purpose, this paper first derives the relative permittivity estimation model with measured RSSI information. Then, we pay attention to a particle filter algorithm with the TOA-based localization and the RSSI-based relative permittivity estimation. Our computer simulation results demonstrates that the proposed tracking methods with the particle filter can accomplish an excellent localization accuracy of around 2 mm without prior information of the relative permittivity of the human body tissues.

  15. The 2006 July 17 Java (Indonesia) tsunami from satellite imagery and numerical modelling: a single or complex source?

    Science.gov (United States)

    Hébert, H.; Burg, P.-E.; Binet, R.; Lavigne, F.; Allgeyer, S.; Schindelé, F.

    2012-12-01

    The Mw 7.8 2006 July 17 earthquake off the southern coast of Java, Indonesia, has been responsible for a very large tsunami causing more than 700 casualties. The tsunami has been observed on at least 200 km of coastline in the region of Pangandaran (West Java), with run-up heights from 5 to more than 20 m. Such a large tsunami, with respect to the source magnitude, has been attributed to the slow character of the seismic rupture, defining the event as a so-called tsunami earthquake, but it has also been suggested that the largest run-up heights are actually the result of a second local landslide source. Here we test whether a single slow earthquake source can explain the tsunami run-up, using a combination of new detailed data in the region of the largest run-ups and comparison with modelled run-ups for a range of plausible earthquake source models. Using high-resolution satellite imagery (SPOT 5 and Quickbird), the coastal impact of the tsunami is refined in the surroundings of the high-security Permisan prison on Nusa Kambangan island, where 20 m run-up had been recorded directly after the event. These data confirm the extreme inundation lengths close to the prison, and extend the area of maximum impact further along the Nusa Kambangan island (about 20 km of shoreline), where inundation lengths reach several hundreds of metres, suggesting run-up as high as 10-15 m. Tsunami modelling has been conducted in detail for the high run-up Permisan area (Nusa Kambangan) and the PLTU power plant about 25 km eastwards, where run-up reached only 4-6 m and a video recording of the tsunami arrival is available. For the Permisan prison a high-resolution DEM was built from stereoscopic satellite imagery. The regular basin of the PLTU plant was designed using photographs and direct observations. For the earthquake's mechanism, both static (infinite) and finite (kinematic) ruptures are investigated using two published source models. The models account rather well for the sea level

  16. A radiation closure study of Arctic stratus cloud microphysical properties using the collocated satellite-surface data and Fu-Liou radiative transfer model

    Science.gov (United States)

    Dong, Xiquan; Xi, Baike; Qiu, Shaoyue; Minnis, Patrick; Sun-Mack, Sunny; Rose, Fred

    2016-09-01

    Retrievals of cloud microphysical properties based on passive satellite imagery are especially difficult over snow-covered surfaces because of the bright and cold surface. To help quantify their uncertainties, single-layered overcast liquid-phase Arctic stratus cloud microphysical properties retrieved by using the Clouds and the Earth's Radiant Energy System Edition 2 and Edition 4 (CERES Ed2 and Ed4) algorithms are compared with ground-based retrievals at the Atmospheric Radiation Measurement North Slope of Alaska (ARM NSA) site at Barrow, AK, during the period from March 2000 to December 2006. A total of 206 and 140 snow-free cases (Rsfc ≤ 0.3), and 108 and 106 snow cases (Rsfc > 0.3), respectively, were selected from Terra and Aqua satellite passes over the ARM NSA site. The CERES Ed4 and Ed2 optical depth (τ) and liquid water path (LWP) retrievals from both Terra and Aqua are almost identical and have excellent agreement with ARM retrievals under snow-free and snow conditions. In order to reach a radiation closure study for both the surface and top of atmosphere (TOA) radiation budgets, the ARM precision spectral pyranometer-measured surface albedos were adjusted (63.6% and 80% of the ARM surface albedos for snow-free and snow cases, respectively) to account for the water and land components of the domain of 30 km × 30 km. Most of the radiative transfer model calculated SW↓sfc and SW↑TOA fluxes by using ARM and CERES cloud retrievals and the domain mean albedos as input agree with the ARM and CERES flux observations within 10 W m-2 for both snow-free and snow conditions. Sensitivity studies show that the ARM LWP and re retrievals are less dependent on solar zenith angle (SZA), but all retrieved optical depths increase with SZA.

  17. RETRIEVAL OF AEROSOL MICROPHYSICAL PROPERTIES BASED ON THE OPTIMAL ESTIMATION METHOD: INFORMATION CONTENT ANALYSIS FOR SATELLITE POLARIMETRIC REMOTE SENSING MEASUREMENTS

    Directory of Open Access Journals (Sweden)

    W. Z. Hou

    2018-04-01

    Full Text Available This paper evaluates the information content for the retrieval of key aerosol microphysical and surface properties for multispectral single-viewing satellite polarimetric measurements cantered at 410, 443, 555, 670, 865, 1610 and 2250 nm over bright land. To conduct the information content analysis, the synthetic data are simulated by the Unified Linearized Vector Radiative Transfer Model (UNLVTM with the intensity and polarization together over bare soil surface for various scenarios. Following the optimal estimation theory, a principal component analysis method is employed to reconstruct the multispectral surface reflectance from 410 nm to 2250 nm, and then integrated with a linear one-parametric BPDF model to represent the contribution of polarized surface reflectance, thus further to decouple the surface-atmosphere contribution from the TOA measurements. Focusing on two different aerosol models with the aerosol optical depth equal to 0.8 at 550 nm, the total DFS and DFS component of each retrieval aerosol and surface parameter are analysed. The DFS results show that the key aerosol microphysical properties, such as the fine- and coarse-mode columnar volume concentration, the effective radius and the real part of complex refractive index at 550 nm, could be well retrieved with the surface parameters simultaneously over bare soil surface type. The findings of this study can provide the guidance to the inversion algorithm development over bright surface land by taking full use of the single-viewing satellite polarimetric measurements.

  18. Retrieval of Aerosol Microphysical Properties Based on the Optimal Estimation Method: Information Content Analysis for Satellite Polarimetric Remote Sensing Measurements

    Science.gov (United States)

    Hou, W. Z.; Li, Z. Q.; Zheng, F. X.; Qie, L. L.

    2018-04-01

    This paper evaluates the information content for the retrieval of key aerosol microphysical and surface properties for multispectral single-viewing satellite polarimetric measurements cantered at 410, 443, 555, 670, 865, 1610 and 2250 nm over bright land. To conduct the information content analysis, the synthetic data are simulated by the Unified Linearized Vector Radiative Transfer Model (UNLVTM) with the intensity and polarization together over bare soil surface for various scenarios. Following the optimal estimation theory, a principal component analysis method is employed to reconstruct the multispectral surface reflectance from 410 nm to 2250 nm, and then integrated with a linear one-parametric BPDF model to represent the contribution of polarized surface reflectance, thus further to decouple the surface-atmosphere contribution from the TOA measurements. Focusing on two different aerosol models with the aerosol optical depth equal to 0.8 at 550 nm, the total DFS and DFS component of each retrieval aerosol and surface parameter are analysed. The DFS results show that the key aerosol microphysical properties, such as the fine- and coarse-mode columnar volume concentration, the effective radius and the real part of complex refractive index at 550 nm, could be well retrieved with the surface parameters simultaneously over bare soil surface type. The findings of this study can provide the guidance to the inversion algorithm development over bright surface land by taking full use of the single-viewing satellite polarimetric measurements.

  19. CERES ERBE-like Instantaneous TOA Estimates (ES-8) in HDF (CER_ES4_TRMM-PFM_Edition1)

    Science.gov (United States)

    Wielicki, Bruce A. (Principal Investigator)

    The ERBE-like Monthly Geographical Averages (ES-4) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The ES-4 is also produced for combinations of scanner instruments. For each observed 2.5-degree spatial region, the daily average, the hourly average over the month, and the overall monthly average of shortwave and longwave fluxes at the Top-of-the-Atmosphere (TOA) from the CERES ES-9 product are spatially nested up from 2.5-degree regions to 5- and 10-degree regions, to 2.5-, 5-, and 10-degree zonal averages, and to global monthly averages. For each nested area, the albedo and net flux are given. For each region, the daily average flux is estimated from an algorithm that uses the available hourly data, scene identification data, and diurnal models. This algorithm is 'like' the algorithm used for the Earth Radiation Budget Experiment (ERBE). The following CERES ES4 data sets are currently available: CER_ES4_FM1+FM2_Edition1 CER_ES4_PFM+FM1+FM2_Edition1 CER_ES4_PFM+FM1+FM2_Edition2 CER_ES4_PFM+FM1_Edition1 CER_ES4_PFM+FM2_Edition1 CER_ES4_TRMM-PFM_Edition1 CER_ES4_TRMM-PFM_Edition2 CER_ES4_Terra-FM1_Edition1 CER_ES4_Terra-FM2_Edition1 CER_ES4_FM1+FM2_Edition2 CER_ES4_Terra-FM1_Edition2 CER_ES4_Terra-FM2_Edition2 CER_ES4_Aqua-FM3_Edition1 CER_ES4_Aqua-FM4_Edition1 CER_ES4_FM1+FM2+FM3+FM4_Edition1 CER_ES4_Aqua-FM3_Edition2 CER_ES4_Aqua-FM4_Edition2 CER_ES4_FM1+FM3_Edition2 CER_ES4_FM1+FM4_Edition2 CER_ES4_PFM+FM1_Edition2 CER_ES4_PFM+FM2_Edition2 CER_ES4_Aqua-FM3_Edition1-CV CER_ES4_Aqua-FM4_Edition1-CV CER_ES4_Terra-FM1_Edition1-CV CER_ES4_Terra-FM2_Edition1-CV. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=1998-08-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=2.5 degree; Longitude_Resolution=2.5 degree; Horizontal

  20. Determination of traces of 237Np in environmental samples by ICP-MS after separation using TOA extraction chromatography

    International Nuclear Information System (INIS)

    Ji, Y.Q.; Li, J.Y.; Luo, S.G.; Wu, T.; Liu, J.L.

    2001-01-01

    A simple, rapid, cost-efficient, and robust method for separation of 237 Np with an extraction chromatographic column (TOA: tri-n-octylamine on Teflon powder) is outlined in detail and further improved for direct ICP-MS analysis. The column efficiently retained 237 Np in 2 mol L -1 HNO 3 medium and all of the 237 Np was easily eluted with 0.02 mol L -1 oxalic acid in 0.16 mol L -1 HNO 3 at 95 C. The separated solutions were free from most matrix elements and were aspirated into the ICP-MS directly. The decontamination factor for 238 U is more than 10 4 . The instrumental detection limit for 237 Np was 0.46 pg mL -1 , which corresponds to 1.2 x 10 -5 Bq mL -1 . The method is more rapid than traditional radiometric techniques. It is also considered to be more suitable for environmental monitoring than existing methods based on TOA. (orig.)

  1. Determination of traces of 237Np in environmental samples by ICP-MS after separation using TOA extraction chromatography.

    Science.gov (United States)

    Ji, Y Q; Li, J Y; Luo, S G; Wu, T; Liu, J L

    2001-09-01

    A simple, rapid, cost-efficient, and robust method for separation of 237Np with an extraction chromatographic column (TOA: tri-n-octylamine on Teflon powder) is outlined in detail and further improved for direct ICP-MS analysis. The column efficiently retained 237Np in 2 mol L(-1) HNO3 medium and all of the 237Np was easily eluted with 0.02 mol L(-1) oxalic acid in 0.16 mol L(-1) HNO3 at 95 degrees C. The separated solutions were free from most matrix elements and were aspirated into the ICP-MS directly. The decontamination factor for 238U is more than 10(4). The instrumental detection limit for 237Np was 0.46 pg mL(-1), which corresponds to 1.2 x 10(-5) Bq mL(-1). The method is more rapid than traditional radiometric techniques. It is also considered to be more suitable for environmental monitoring than existing methods based on TOA.

  2. Shadow Analysis Technique for Extraction of Building Height using High Resolution Satellite Single Image and Accuracy Assessment

    Science.gov (United States)

    Raju, P. L. N.; Chaudhary, H.; Jha, A. K.

    2014-11-01

    These High resolution satellite data with metadata information is used to extract the height of the building using shadow. Proposed approach divides into two phases 1) rooftop and shadow extraction and 2) height estimation. Firstly the rooftop and shadow region were extracted by manual/ automatic methods using Example - Based and Rule - Based approaches. After feature extraction next step is estimating height of the building by taking rooftop in association with shadow using Ratio Method and by using the relation between sun-satellite geometry. The performance analysis shows the total mean error of height is 0.67 m from ratio method, 1.51 m from Example - Based Approach and 0.96 m from Rule - Based Approach. Analysis concluded that Ratio Method i.e. manual method is best for height estimation but it is time consuming so the automatic Rule Based approach is best for height estimation in comparison to Example Based Approach because it require more knowledge and selection of more training samples as well as slows the processing rate of the method.

  3. Sensitivity of Satellite-Based Skin Temperature to Different Surface Emissivity and NWP Reanalysis Sources Demonstrated Using a Single-Channel, Viewing-Angle-Corrected Retrieval Algorithm

    Science.gov (United States)

    Scarino, B. R.; Minnis, P.; Yost, C. R.; Chee, T.; Palikonda, R.

    2015-12-01

    Single-channel algorithms for satellite thermal-infrared- (TIR-) derived land and sea surface skin temperature (LST and SST) are advantageous in that they can be easily applied to a variety of satellite sensors. They can also accommodate decade-spanning instrument series, particularly for periods when split-window capabilities are not available. However, the benefit of one unified retrieval methodology for all sensors comes at the cost of critical sensitivity to surface emissivity (ɛs) and atmospheric transmittance estimation. It has been demonstrated that as little as 0.01 variance in ɛs can amount to more than a 0.5-K adjustment in retrieved LST values. Atmospheric transmittance requires calculations that employ vertical profiles of temperature and humidity from numerical weather prediction (NWP) models. Selection of a given NWP model can significantly affect LST and SST agreement relative to their respective validation sources. Thus, it is necessary to understand the accuracies of the retrievals for various NWP models to ensure the best LST/SST retrievals. The sensitivities of the single-channel retrievals to surface emittance and NWP profiles are investigated using NASA Langley historic land and ocean clear-sky skin temperature (Ts) values derived from high-resolution 11-μm TIR brightness temperature measured from geostationary satellites (GEOSat) and Advanced Very High Resolution Radiometers (AVHRR). It is shown that mean GEOSat-derived, anisotropy-corrected LST can vary by up to ±0.8 K depending on whether CERES or MODIS ɛs sources are used. Furthermore, the use of either NOAA Global Forecast System (GFS) or NASA Goddard Modern-Era Retrospective Analysis for Research and Applications (MERRA) for the radiative transfer model initial atmospheric state can account for more than 0.5-K variation in mean Ts. The results are compared to measurements from the Surface Radiation Budget Network (SURFRAD), an Atmospheric Radiation Measurement (ARM) Program ground

  4. Retrieval of land surface temperature (LST) from landsat TM6 and TIRS data by single channel radiative transfer algorithm using satellite and ground-based inputs

    Science.gov (United States)

    Chatterjee, R. S.; Singh, Narendra; Thapa, Shailaja; Sharma, Dravneeta; Kumar, Dheeraj

    2017-06-01

    The present study proposes land surface temperature (LST) retrieval from satellite-based thermal IR data by single channel radiative transfer algorithm using atmospheric correction parameters derived from satellite-based and in-situ data and land surface emissivity (LSE) derived by a hybrid LSE model. For example, atmospheric transmittance (τ) was derived from Terra MODIS spectral radiance in atmospheric window and absorption bands, whereas the atmospheric path radiance and sky radiance were estimated using satellite- and ground-based in-situ solar radiation, geographic location and observation conditions. The hybrid LSE model which is coupled with ground-based emissivity measurements is more versatile than the previous LSE models and yields improved emissivity values by knowledge-based approach. It uses NDVI-based and NDVI Threshold method (NDVITHM) based algorithms and field-measured emissivity values. The model is applicable for dense vegetation cover, mixed vegetation cover, bare earth including coal mining related land surface classes. The study was conducted in a coalfield of India badly affected by coal fire for decades. In a coal fire affected coalfield, LST would provide precise temperature difference between thermally anomalous coal fire pixels and background pixels to facilitate coal fire detection and monitoring. The derived LST products of the present study were compared with radiant temperature images across some of the prominent coal fire locations in the study area by graphical means and by some standard mathematical dispersion coefficients such as coefficient of variation, coefficient of quartile deviation, coefficient of quartile deviation for 3rd quartile vs. maximum temperature, coefficient of mean deviation (about median) indicating significant increase in the temperature difference among the pixels. The average temperature slope between adjacent pixels, which increases the potential of coal fire pixel detection from background pixels, is

  5. Solar satellites

    Energy Technology Data Exchange (ETDEWEB)

    Poher, C.

    1982-01-01

    A reference system design, projected costs, and the functional concepts of a satellite solar power system (SSPS) for converting sunlight falling on solar panels of a satellite in GEO to a multi-GW beam which could be received by a rectenna on earth are outlined. Electricity transmission by microwaves has been demonstrated, and a reference design system for supplying 5 GW dc to earth was devised. The system will use either monocrystalline Si or concentrator GaAs solar cells for energy collection in GEO. Development is still needed to improve the lifespan of the cells. Currently, the cell performance degrades 50 percent in efficiency after 7-8 yr in space. Each SSPS satellite would weigh either 34,000 tons (Si) or 51,000 tons (GaAs), thereby requiring the fabrication of a heavy lift launch vehicle or a single-stage-to-orbit transport in order to minimize launch costs. Costs for the solar panels have been estimated at $500/kW using the GaAs technology, with transport costs for materials to GEO being $40/kg.

  6. Solar satellites

    Science.gov (United States)

    Poher, C.

    A reference system design, projected costs, and the functional concepts of a satellite solar power system (SSPS) for converting sunlight falling on solar panels of a satellite in GEO to a multi-GW beam which could be received by a rectenna on earth are outlined. Electricity transmission by microwaves has been demonstrated, and a reference design system for supplying 5 GW dc to earth was devised. The system will use either monocrystalline Si or concentrator GaAs solar cells for energy collection in GEO. Development is still needed to improve the lifespan of the cells. Currently, the cell performance degrades 50 percent in efficiency after 7-8 yr in space. Each SSPS satellite would weigh either 34,000 tons (Si) or 51,000 tons (GaAs), thereby requiring the fabrication of a heavy lift launch vehicle or a single-stage-to-orbit transport in order to minimize launch costs. Costs for the solar panels have been estimated at $500/kW using the GaAs technology, with transport costs for materials to GEO being $40/kg.

  7. Complete Genomes of Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, Two Phylogenetically Distinct Probiotics

    Science.gov (United States)

    Ramya, T. N. C.; Subramanian, Srikrishna

    2016-01-01

    Several spore-forming strains of Bacillus are marketed as probiotics due to their ability to survive harsh gastrointestinal conditions and confer health benefits to the host. We report the complete genomes of two commercially available probiotics, Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, and compare them with the genomes of other Bacillus and Lactobacillus. The taxonomic position of both organisms was established with a maximum-likelihood tree based on twenty six housekeeping proteins. Analysis of all probiotic strains of Bacillus and Lactobacillus reveal that the essential sporulation proteins are conserved in all Bacillus probiotic strains while they are absent in Lactobacillus spp. We identified various antibiotic resistance, stress-related, and adhesion-related domains in these organisms, which likely provide support in exerting probiotic action by enabling adhesion to host epithelial cells and survival during antibiotic treatment and harsh conditions. PMID:27258038

  8. Complete Genomes of Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, Two Phylogenetically Distinct Probiotics.

    Directory of Open Access Journals (Sweden)

    Indu Khatri

    Full Text Available Several spore-forming strains of Bacillus are marketed as probiotics due to their ability to survive harsh gastrointestinal conditions and confer health benefits to the host. We report the complete genomes of two commercially available probiotics, Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, and compare them with the genomes of other Bacillus and Lactobacillus. The taxonomic position of both organisms was established with a maximum-likelihood tree based on twenty six housekeeping proteins. Analysis of all probiotic strains of Bacillus and Lactobacillus reveal that the essential sporulation proteins are conserved in all Bacillus probiotic strains while they are absent in Lactobacillus spp. We identified various antibiotic resistance, stress-related, and adhesion-related domains in these organisms, which likely provide support in exerting probiotic action by enabling adhesion to host epithelial cells and survival during antibiotic treatment and harsh conditions.

  9. Complete Genomes of Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, Two Phylogenetically Distinct Probiotics.

    Science.gov (United States)

    Khatri, Indu; Sharma, Shailza; Ramya, T N C; Subramanian, Srikrishna

    2016-01-01

    Several spore-forming strains of Bacillus are marketed as probiotics due to their ability to survive harsh gastrointestinal conditions and confer health benefits to the host. We report the complete genomes of two commercially available probiotics, Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, and compare them with the genomes of other Bacillus and Lactobacillus. The taxonomic position of both organisms was established with a maximum-likelihood tree based on twenty six housekeeping proteins. Analysis of all probiotic strains of Bacillus and Lactobacillus reveal that the essential sporulation proteins are conserved in all Bacillus probiotic strains while they are absent in Lactobacillus spp. We identified various antibiotic resistance, stress-related, and adhesion-related domains in these organisms, which likely provide support in exerting probiotic action by enabling adhesion to host epithelial cells and survival during antibiotic treatment and harsh conditions.

  10. Influencia del Estado de Oxidación del Ión Cobalto en la Estabilidad de Electrodos Modificados con Monocapas SAM-TOA-ANTA-Con+-HRP-NHis.

    Directory of Open Access Journals (Sweden)

    Pedro R. Matheus*

    Full Text Available Influence of state oxidation of cobalt ion in the stability electrodes modified with monolayers SAM-TOA-ANTA-Con+-HRP-NHis. Quartz Crystal Microbalance (QCM was used to investigate the adsorption of the HRP-NHis enzyme (horseradish peroxidase, which was modified by the addition of a tail of six histidine on its extreme N-terminal. The QCM operating at flow of 0.025 mL min-1 on a crystal whose gold electrode was modified with monolayers of SAM-TOA-ANTA-Co2+ and SAM-TOA-ANTA -Co3+. The oxidize form was obtained from the electrochemical oxidation of a monolayer of SAM-TOA-ANTA-Co2+. The results suggest that the HRP-NHis is attached to both monolayers in a similar way; on the contrary, the desortion of the attached protein is dramatically different. Thus, whereas the ligand-Co2+ bonds are reversible, which allows that the anchored protein is easily replaced by imidazol molecules. The 3+ oxidation state of the metal does not allow the interchange of protein by the imidazol molecules.

  11. , , , , , and Gene Expression in Single- and Co-cultured Bovine Satellite Cells and Intramuscular Preadipocytes Treated with Palmitic, Stearic, Oleic, and Linoleic Acid

    Directory of Open Access Journals (Sweden)

    S. H. Choi

    2015-03-01

    Full Text Available We previously demonstrated that bovine subcutaneous preadipocytes promote adipogenic gene expression in muscle satellite cells in a co-culture system. Herein we hypothesize that saturated fatty acids would promote adipogenic/lipogenic gene expression, whereas mono- and polyunsaturated fatty acids would have the opposite effect. Bovine semimembranosus satellite cells (BSC and intramuscular preadipocytes (IPA were isolated from crossbred steers and cultured with 10% fetal bovine serum (FBS/Dulbecco’s Modified Eagle Medium (DMEM and 1% antibiotics during the 3-d proliferation period. After proliferation, cells were treated for 3 d with 3% horse serum/DMEM (BSC or 5% FBS/DMEM (IPA with antibiotics. Media also contained 10 μg/mL insulin and 10 μg/mL pioglitazone. Subsequently, differentiating BSC and IPA were cultured in their respective media with 40 μM palmitic, stearic, oleic, or linoleic acid for 4 d. Finally, BSC and IPA were single- or co-cultured for an additional 2 h. All fatty acid treatments increased (p = 0.001 carnitine palmitoyltransferase-1 beta (CPT1β gene expression, but the increase in CPT1β gene expression was especially pronounced in IPA incubated with palmitic and stearic acid (6- to 17- fold increases. Oleic and linoleic acid decreased (p = 0.001 stearoyl-CoA desaturase (SCD gene expression over 80% in both BSC and IPA. Conversely, palmitic and stearic acid increased SCD gene expression three fold in co-cultured in IPA, and stearic acid increased AMPKα gene expression in single- and co-cultured BSC and IPA. Consistent with our hypothesis, saturated fatty acids, especially stearic acid, promoted adipogenic and lipogenic gene expression, whereas unsaturated fatty acids decreased expression of those genes associated with fatty acid metabolism.

  12. From a single encapsulated detector to the spectrometer for INTEGRAL satellite: predicting the peak-to-total ratio at high γ-energies

    International Nuclear Information System (INIS)

    Kshetri, R

    2012-01-01

    In two recent papers (R. Kshetri, JINST 2012 7 P04008; ibid., P07006), a probabilistic formalism was introduced to predict the response of encapsulated type composite germanium detectors like the SPI (spectrometer for INTEGRAL satellite). Predictions for the peak-to-total and peak-to-background ratios are given at 1.3 MeV for the addback mode of operation. The application of the formalism to clover germanium detector is discussed in two separate papers (R. Kshetri, JINST 2012 7 P07008; ibid., P08015). Using the basic approach developed in those papers, for the first time we present a procedure for calculating the peak-to-total ratio of the cluster detector for γ-energies up to 8 MeV. Results are shown for both bare and suppressed detectors as well as for the single crystal and addback modes of operation. We have considered the experimental data of (i) peak-to-total ratio at 1.3 MeV, and (ii) single detector efficiency and addback factor for other energies up to 8 MeV. Using this data, an approximate method of calculating the peak-to-total ratio of other composite detectors, is shown. Experimental validation of our approach (for energies up to 8 MeV) has been confirmed considering the data of the SPI spectrometer. We have discussed about comparisons between various modes of operation and suppression cases. The present paper is the fifth in the series of papers on composite germanium detectors and for the first time discusses about the change in fold distribution and peak-to-total ratio for sophisticated detectors consisting of several modules of miniball, cluster and SPI detectors. Our work could provide a guidance in designing new composite detectors and in performing experimental studies with the existing detectors for high energy gamma-rays.

  13. From a single encapsulated detector to the spectrometer for INTEGRAL satellite: predicting the peak-to-total ratio at high γ-energies

    Science.gov (United States)

    Kshetri, R.

    2012-12-01

    In two recent papers (R. Kshetri, JINST 2012 7 P04008; ibid., P07006), a probabilistic formalism was introduced to predict the response of encapsulated type composite germanium detectors like the SPI (spectrometer for INTEGRAL satellite). Predictions for the peak-to-total and peak-to-background ratios are given at 1.3 MeV for the addback mode of operation. The application of the formalism to clover germanium detector is discussed in two separate papers (R. Kshetri, JINST 2012 7 P07008; ibid., P08015). Using the basic approach developed in those papers, for the first time we present a procedure for calculating the peak-to-total ratio of the cluster detector for γ-energies up to 8 MeV. Results are shown for both bare and suppressed detectors as well as for the single crystal and addback modes of operation. We have considered the experimental data of (i) peak-to-total ratio at 1.3 MeV, and (ii) single detector efficiency and addback factor for other energies up to 8 MeV. Using this data, an approximate method of calculating the peak-to-total ratio of other composite detectors, is shown. Experimental validation of our approach (for energies up to 8 MeV) has been confirmed considering the data of the SPI spectrometer. We have discussed about comparisons between various modes of operation and suppression cases. The present paper is the fifth in the series of papers on composite germanium detectors and for the first time discusses about the change in fold distribution and peak-to-total ratio for sophisticated detectors consisting of several modules of miniball, cluster and SPI detectors. Our work could provide a guidance in designing new composite detectors and in performing experimental studies with the existing detectors for high energy gamma-rays.

  14. Examination of aerosol distributions and radiative effects over the Bay of Bengal and the Arabian Sea region during ICARB using satellite data and a general circulation model

    Directory of Open Access Journals (Sweden)

    R. Cherian

    2012-02-01

    Full Text Available In this paper we analyse aerosol loading and its direct radiative effects over the Bay of Bengal (BoB and Arabian Sea (AS regions for the Integrated Campaign on Aerosols, gases and Radiation Budget (ICARB undertaken during 2006, using satellite data from the MODerate Resolution Imaging Spectroradiometer (MODIS on board the Terra and Aqua satellites, the Aerosol Index from the Ozone Monitoring Instrument (OMI on board the Aura satellite, and the European-Community Hamburg (ECHAM5.5 general circulation model extended by Hamburg Aerosol Module (HAM. By statistically comparing with large-scale satellite data sets, we firstly show that the aerosol properties measured during the ship-based ICARB campaign and simulated by the model are representative for the BoB and AS regions and the pre-monsoon season. In a second step, the modelled aerosol distributions were evaluated by a comparison with the measurements from the ship-based sunphotometer, and the satellite retrievals during ICARB. It is found that the model broadly reproduces the observed spatial and temporal variability in aerosol optical depth (AOD over BoB and AS regions. However, AOD was systematically underestimated during high-pollution episodes, especially in the BoB leg. We show that this underprediction of AOD is mostly because of the deficiencies in the coarse mode, where the model shows that dust is the dominant component. The analysis of dust AOD along with the OMI Aerosol Index indicate that missing dust transport that results from too low dust emission fluxes over the Thar Desert region in the model caused this deficiency. Thirdly, we analysed the spatio-temporal variability of AOD comparing the ship-based observations to the large-scale satellite observations and simulations. It was found that most of the variability along the track was from geographical patterns, with a minor influence by single events. Aerosol fields were homogeneous enough to yield a good statistical agreement

  15. Saturn satellites

    International Nuclear Information System (INIS)

    Ruskol, E.L.

    1981-01-01

    The characteristics of the Saturn satellites are discussed. The satellites close to Saturn - Janus, Mimas, Enceladus, Tethys, Dione and Rhea - rotate along the circular orbits. High reflectivity is attributed to them, and the density of the satellites is 1 g/cm 3 . Titan is one of the biggest Saturn satellites. Titan has atmosphere many times more powerful than that of Mars. The Titan atmosphere is a peculiar medium with a unique methane and hydrogen distribution in the whole Solar system. The external satellites - Hyperion, Japetus and Phoebe - are poorly investigated. Neither satellite substance density, nor their composition are known. The experimental data on the Saturn rings obtained on the ''Pioneer-11'' and ''Voyager-1'' satellites are presented [ru

  16. Clock Management Data Analysis for Satellite Communications

    National Research Council Canada - National Science Library

    Gross, Rachel; Melkers, Raimond

    2005-01-01

    The U.S. Naval Research Laboratory has installed GPS-based timing systems in several Defense Satellite Communication System "DSCS-III" satellite communication facilities to support the Single Channel Transponder "SCT" program...

  17. Centriolar satellites

    DEFF Research Database (Denmark)

    Tollenaere, Maxim A X; Mailand, Niels; Bekker-Jensen, Simon

    2015-01-01

    Centriolar satellites are small, microscopically visible granules that cluster around centrosomes. These structures, which contain numerous proteins directly involved in centrosome maintenance, ciliogenesis, and neurogenesis, have traditionally been viewed as vehicles for protein trafficking...... highlight newly discovered regulatory mechanisms targeting centriolar satellites and their functional status, and we discuss how defects in centriolar satellite components are intimately linked to a wide spectrum of human diseases....

  18. Satellite Communications

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Satellite Communications. Arthur C Clarke wrote a seminal paper in 1945 in wireless world. Use three satellites in geo-synchronous orbit to enable intercontinental communications. System could be realised in '50 to 100 years'

  19. Satellite Communications

    CERN Document Server

    Pelton, Joseph N

    2012-01-01

    The field of satellite communications represents the world's largest space industry. Those who are interested in space need to understand the fundamentals of satellite communications, its technology, operation, business, economic, and regulatory aspects. This book explains all this along with key insights into the field's future growth trends and current strategic challenges. Fundamentals of Satellite Communications is a concise book that gives all of the key facts and figures as well as a strategic view of where this dynamic industry is going. Author Joseph N. Pelton, PhD, former Dean of the International Space University and former Director of Strategic Policy at Intelstat, presents a r

  20. Cambrian origin of the CYP27C1-mediated vitamin A1-to-A2 switch, a key mechanism of vertebrate sensory plasticity

    Science.gov (United States)

    Morshedian, Ala; Toomery, Matthew B.; Pollock, Gabriel E.; Frederiksen, Rikard; Enright, Jennifer; McCormick, Stephen; Cornwall, M. Carter; Fain, Gordon L.; Corbo, Joseph C.

    2017-01-01

    The spectral composition of ambient light varies across both space and time. Many species of jawed vertebrates adapt to this variation by tuning the sensitivity of their photoreceptors via the expression of CYP27C1, an enzyme that converts vitamin A1 into vitamin A2, thereby shifting the ratio of vitamin A1-based rhodopsin to red-shifted vitamin A2-based porphyropsin in the eye. Here, we show that the sea lamprey (Petromyzon marinus), a jawless vertebrate that diverged from jawed vertebrates during the Cambrian period (approx. 500 Ma), dynamically shifts its photoreceptor spectral sensitivity via vitamin A1-to-A2 chromophore exchange as it transitions between photically divergent aquatic habitats. We further show that this shift correlates with high-level expression of the lamprey orthologue of CYP27C1, specifically in the retinal pigment epithelium as in jawed vertebrates. Our results suggest that the CYP27C1-mediated vitamin A1-to-A2 switch is an evolutionarily ancient mechanism of sensory plasticity that appeared not long after the origin of vertebrates.

  1. Satellite myths

    Science.gov (United States)

    Easton, Roger L.; Hall, David

    2008-01-01

    Richard Corfield's article “Sputnik's legacy” (October 2007 pp23-27) states that the satellite on board the US Vanguard rocket, which exploded during launch on 6 December 1957 two months after Sputnik's successful take-off, was “a hastily put together contraption of wires and circuitry designed only to send a radio signal back to Earth”. In fact, the Vanguard satellite was developed over a period of several years and put together carefully using the best techniques and equipment available at the time - such as transistors from Bell Laboratories/Western Electric. The satellite contained not one but two transmitters, in which the crystal-controlled oscillators had been designed to measure both the temperature of the satellite shell and of the internal package.

  2. Satellite Geomagnetism

    DEFF Research Database (Denmark)

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade....... The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite constellation Swarm will ensure continuity of such measurement and provide enhanced possibilities to improve our...... ability to characterize and understand the many sources that contribute to Earth’s magnetic field. In this review, we summarize investigations of Earth’s interior and environment that have been possible through the analysis of high-precision magnetic field observations taken by LEO satellites....

  3. Boomerang Satellites

    Science.gov (United States)

    Hesselbrock, Andrew; Minton, David A.

    2017-10-01

    We recently reported that the orbital architecture of the Martian environment allows for material in orbit around the planet to ``cycle'' between orbiting the planet as a ring, or as coherent satellites. Here we generalize our previous analysis to examine several factors that determine whether satellites accreting at the edge of planetary rings will cycle. In order for the orbiting material to cycle, tidal evolution must decrease the semi-major axis of any accreting satellites. In some systems, the density of the ring/satellite material, the surface mass density of the ring, the tidal parameters of the system, and the rotation rate of the primary body contribute to a competition between resonant ring torques and tidal dissipation that prevent this from occurring, either permanently or temporarily. Analyzing these criteria, we examine various bodies in our solar system (such as Saturn, Uranus, and Eris) to identify systems where cycling may occur. We find that a ring-satellite cycle may give rise to the current Uranian ring-satellite system, and suggest that Miranda may have formed from an early, more massive Uranian ring.

  4. A Study of the Oklahoma City Urban Heat Island Effect Using a WRF/Single-Layer Urban Canopy Model, a Joint Urban 2003 Field Campaign, and MODIS Satellite Observations

    Directory of Open Access Journals (Sweden)

    Hengyue Zhang

    2017-09-01

    Full Text Available The urban heat island effect (UHI for inner land regions was investigated using satellite data, ground observations, and simulations with an Single-Layer Urban Canopy Parameterization (SLUCP coupled into the regional Weather Research Forecasting model (WRF, http://wrf-model.org/index.php. Specifically, using the satellite-observed surface skin temperatures (Tskin, the intensity of the UHI was first compared for two inland cities (Xi’an City, China, and Oklahoma City (OKC, which have different city populations and building densities. The larger population density and larger building density in Xi’an lead to a stronger skin-level UHI by 2 °C. However, the ground observed 2 m surface air temperature (Tair observations showed an urban cooling island effect (UCI over the downtown region in OKC during the daytime of 19 July 2003, from a DOE field campaign (Joint Urban 2003. To understand this contrast between satellite-based Tskin and ground-based Tair, a sensitivity study using WRF/SLUCP was analyzed. The model reproduced a UCI in OKC. Furthermore, WRF/Noah/SLUCM simulations were also compared with the Joint Urban 2003 ground observations, including wind speeds, wind directions, and energy fluxes. Although the WRF/SLUCM model failed to simulate these variables accurately, it reproduced the diurnal variations of surface temperatures, wind speeds, wind directions, and energy fluxes reasonably well.

  5. From a single encapsulated detector to the spectrometer for INTEGRAL satellite: predicting the peak-to-total ratio at high gamma-energies

    OpenAIRE

    Kshetri, Ritesh

    2012-01-01

    In two recent papers (R. Kshetri, JINST 2012 7 P04008; ibid., P07006), a probabilistic formalism was introduced to predict the response of encapsulated type composite germanium detectors like the SPI (spectrometer for INTEGRAL satellite). Predictions for the peak-to-total and peak-to-background ratios are given at 1.3 MeV for the addback mode of operation. The application of the formalism to clover germanium detector is discussed in two separate papers (R. Kshetri, JINST 2012 7 P07008; ibid.,...

  6. The sequential-separation of Tc, Np and residual U from metal ions -30% TBP/0.5% TOA/n-dodecane extraction system

    International Nuclear Information System (INIS)

    Lee, I. H.; Kim, S. H.; Lim, J. K.; Kim, K. W.; Kwon, S. K.

    2002-01-01

    This study on the enhancement of Tc extraction and the selective separation of Tc, Np and residual U by means of adding a small amount of tri-n-octylamine(TOA) in the 30% vol. tributyl phosphate(TBP)/n-dodecane was performed. Co-extraction of Tc, Np and U from the 10 components simulated radwaste solution containing the 0.005M-K 2 Cr 2 O 7 as an oxidant of Np by 30% TBP/0.5% TOA, and selective stripping of Tc, Np and U from the loaded organic phase were investigated, and their operation conditions were evaluated. Tc, Np and U was effectively co-extracted at O/A=1 and 1M HNO 3 . In this condition, the co-extraction yields of Tc, Np and U were 81.9%, 86%, 89.2%, respectively and those of Am, Eu, Nd, Mo and Fe were below 5%. For the selective stripping of extracted Tc, Np and U, however, sequentially 5M HNO 3 and O/A=1 for Tc, reduction of Np(VI) to Np(V) with 0.175M n-butyraldehyde (NBA) and O/A=2 for Np, and 0.15M Na 2 CO 3 and O/A=1 for U were used, respectively. In this case, 79% of Tc(co-stripping of less than 4% Np and U), 84% of Np(co-stripping of about 6% U), above 99% of U could be recovered, respectively

  7. Satellite Radio

    Indian Academy of Sciences (India)

    Satellites have been a highly effective platform for multi- form broadcasts. This has led to a ... diversity offormats, languages, genre, and a universal reach that cannot be met by .... programs can be delivered to whom it is intended. In the case of.

  8. The Skeletal Muscle Satellite Cell

    Science.gov (United States)

    2011-01-01

    The skeletal muscle satellite cell was first described and named based on its anatomic location between the myofiber plasma and basement membranes. In 1961, two independent studies by Alexander Mauro and Bernard Katz provided the first electron microscopic descriptions of satellite cells in frog and rat muscles. These cells were soon detected in other vertebrates and acquired candidacy as the source of myogenic cells needed for myofiber growth and repair throughout life. Cultures of isolated myofibers and, subsequently, transplantation of single myofibers demonstrated that satellite cells were myogenic progenitors. More recently, satellite cells were redefined as myogenic stem cells given their ability to self-renew in addition to producing differentiated progeny. Identification of distinctively expressed molecular markers, in particular Pax7, has facilitated detection of satellite cells using light microscopy. Notwithstanding the remarkable progress made since the discovery of satellite cells, researchers have looked for alternative cells with myogenic capacity that can potentially be used for whole body cell-based therapy of skeletal muscle. Yet, new studies show that inducible ablation of satellite cells in adult muscle impairs myofiber regeneration. Thus, on the 50th anniversary since its discovery, the satellite cell’s indispensable role in muscle repair has been reaffirmed. PMID:22147605

  9. Mobility management in satellite networks

    Science.gov (United States)

    Johanson, Gary A.

    1995-01-01

    This paper addresses the methods used or proposed for use in multi-beam and/or multi-satellite networks designed to provide Mobile Satellite Services (MSS). Specific topics include beam crossover in the North American Mobile Satellite (MSAT) system as well as registration and live call hand-off for a multi-regional geosynchronous (GEO) satellite based system and a global coverage Low Earth Orbiting (LEO) system. In the MSAT system, the individual satellite beams cover very large geographic areas so the need for live call hand-off was not anticipated. This paper discusses the methods used to keep track of the beam location of the users so that incoming call announcements or other messages may be directed to them. Proposed new GEO systems with large numbers of beams will provide much smaller geographic coverage in individual beams and thus the need arises to keep track of the user's location as well as to provide live call hand-off as the user traverses from beam to beam. This situation also occurs in proposed LEO systems where the problems are worsened by the need for satellite to satellite hand-off as well as beam to beam hand-off within a single satellite. The paper discusses methods to accomplish these handoffs and proposes system architectures to address the various hand-off scenarios.

  10. Scientific Satellites

    Science.gov (United States)

    1967-01-01

    noise signal level exceeds 10 times the normal background. EXPERIMENTS FOR SATELLITE ASTRONOMY 615 ANTENNA MONOPOLE -., PREAMPLFE = BANDPASS-FILTER...OUTPUT TO AND DETECTOR TELEMETRYCHANNELS (18) CALIBRATION NOISE MATRIX CLOCK NOISE SOURCE ’ON’ SOURCE COMMAND F ROM PROGRAMERP ANTENNA MONOPOLE FIGURE 13...Animal Tempera- ture Sensing for Studying the Effect of Prolonged Orbital Flight on the Circadian Rhythms of Pocket Mice . Unmanned Spacecraft Meeting

  11. A Geometry-Based Cycle Slip Detection and Repair Method with Time-Differenced Carrier Phase (TDCP for a Single Frequency Global Position System (GPS + BeiDou Navigation Satellite System (BDS Receiver

    Directory of Open Access Journals (Sweden)

    Chuang Qian

    2016-12-01

    Full Text Available As the field of high-precision applications based on carriers continues to expand, the development of low-cost, small, modular receivers and their application in diverse scenarios and situations with complex data quality has increased the requirements of carrier-phase data preprocessing. A new geometry-based cycle slip detection and repair method based on Global Position System (GPS + BeiDou Navigation Satellite System (BDS is proposed. The method uses a Time-differenced Carrier Phase (TDCP model, which eliminates the Inner-System Bias (ISB between GPS and BDS, and it is conducive to the effective combination of GPS and BDS. It avoids the interference of the noise of the pseudo-range with cycle slip detection, while the cycle slips are preserved as integers. This method does not limit the receiver frequency number, and it is applicable to single-frequency data. The process is divided into two steps to detect and repair cycle slip. The first step is cycle slip detection, using the Improved Local Analysis Method (ILAM to find satellites that have cycle slips; The second step is to repair the cycle slips, including estimating the float solution of changes in ambiguities at the satellites that have cycle slips with the least squares method and the integer solution of the cycle slips by rounding. In the process of rounding, in addition to the success probability, a decimal test is carried out to validate the result. Finally, experiments with filed test data are carried out to prove the effectiveness of this method. The results show that the detectable cycle slips number with GPS + BDS is much greater than that with GPS. The method can also detect the non-integer outliers while fixing the cycle slip. The maximum decimal bias in repair is less than that with GPS. It implies that this method takes full advantages of multi-system.

  12. Ground test of satellite constellation based quantum communication

    OpenAIRE

    Liao, Sheng-Kai; Yong, Hai-Lin; Liu, Chang; Shentu, Guo-Liang; Li, Dong-Dong; Lin, Jin; Dai, Hui; Zhao, Shuang-Qiang; Li, Bo; Guan, Jian-Yu; Chen, Wei; Gong, Yun-Hong; Li, Yang; Lin, Ze-Hong; Pan, Ge-Sheng

    2016-01-01

    Satellite based quantum communication has been proven as a feasible way to achieve global scale quantum communication network. Very recently, a low-Earth-orbit (LEO) satellite has been launched for this purpose. However, with a single satellite, it takes an inefficient 3-day period to provide the worldwide connectivity. On the other hand, similar to how the Iridium system functions in classic communication, satellite constellation (SC) composed of many quantum satellites, could provide global...

  13. Thoughts on why in CESM a more poleward TOA energy imbalance favors more ocean-centric energy transport and weaker ITCZ shift responses

    Science.gov (United States)

    Yu, S.; Pritchard, M. S.

    2017-12-01

    The role of different location of top-of-atmosphere (TOA) solar forcing to the annual-mean, zonal-mean ITCZ location is examined in a dynamic ocean coupled Community Earth System Model. We observe a damped ITCZ shift response that is now a familiar response of coupled GCMs, but a new finding is that the damping efficiency is increases monotonically as the latitudinal location of forcing is moved poleward. More Poleward forcing cases exhibit weaker shifts of the annual-mean ITCZ position consistent with a more ocean-centric cross-equatorial energy partitioning response to the forcing, which is in turn linked to changes in ocean circulation, not thermodynamic structure. The ocean's dynamic response is partly due to Ekman-driven shallow overturning circulation responses, as expected from a recent theory, but also contains a significant Atlantic meridional overturning circulation (AMOC) component--which is in some sense surprising given that it is activated even in near-tropical forcing experiments. Further analysis of the interhemispheric energy budget reveals the surface heating feedback response provides a useful framework for interpreting the cross-equatorial energy transport partitioning between atmosphere and ocean. Overall, the results of this study may help explain the mixed results of the degree of ITCZ shift response to interhemispheric asymmetric forcing documented in coupled GCMs in recent years. Furthermore, the sensitive AMOC response motivates expanding current coupled theoretical frameworks on meridional energy transport partitioning to include effects beyond Ekman transport.

  14. Geostationary Satellite (GOES) Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Visible and Infrared satellite imagery taken from radiometer instruments on SMS (ATS) and GOES satellites in geostationary orbit. These satellites produced...

  15. Aerosol optical properties derived from the DRAGON-NE Asia campaign, and implications for a single-channel algorithm to retrieve aerosol optical depth in spring from Meteorological Imager (MI on-board the Communication, Ocean, and Meteorological Satellite (COMS

    Directory of Open Access Journals (Sweden)

    M. Kim

    2016-02-01

    Full Text Available An aerosol model optimized for northeast Asia is updated with the inversion data from the Distributed Regional Aerosol Gridded Observation Networks (DRAGON-northeast (NE Asia campaign which was conducted during spring from March to May 2012. This updated aerosol model was then applied to a single visible channel algorithm to retrieve aerosol optical depth (AOD from a Meteorological Imager (MI on-board the geostationary meteorological satellite, Communication, Ocean, and Meteorological Satellite (COMS. This model plays an important role in retrieving accurate AOD from a single visible channel measurement. For the single-channel retrieval, sensitivity tests showed that perturbations by 4 % (0.926 ± 0.04 in the assumed single scattering albedo (SSA can result in the retrieval error in AOD by over 20 %. Since the measured reflectance at the top of the atmosphere depends on both AOD and SSA, the overestimation of assumed SSA in the aerosol model leads to an underestimation of AOD. Based on the AErosol RObotic NETwork (AERONET inversion data sets obtained over East Asia before 2011, seasonally analyzed aerosol optical properties (AOPs were categorized by SSAs at 675 nm of 0.92 ± 0.035 for spring (March, April, and May. After the DRAGON-NE Asia campaign in 2012, the SSA during spring showed a slight increase to 0.93 ± 0.035. In terms of the volume size distribution, the mode radius of coarse particles was increased from 2.08 ± 0.40 to 2.14 ± 0.40. While the original aerosol model consists of volume size distribution and refractive indices obtained before 2011, the new model is constructed by using a total data set after the DRAGON-NE Asia campaign. The large volume of data in high spatial resolution from this intensive campaign can be used to improve the representative aerosol model for East Asia. Accordingly, the new AOD data sets retrieved from a single-channel algorithm, which uses a precalculated look-up table (LUT with the new aerosol model

  16. Aerosol Optical Properties Derived from the DRAGON-NE Asia Campaign, and Implications for a Single-Channel Algorithm to Retrieve Aerosol Optical Depth in Spring from Meteorological Imager (MI) On-Board the Communication, Ocean, and Meteorological Satellite (COMS)

    Science.gov (United States)

    Kim, M.; Kim, J.; Jeong, U.; Kim, W.; Hong, H.; Holben, B.; Eck, T. F.; Lim, J.; Song, C.; Lee, S.; hide

    2016-01-01

    An aerosol model optimized for northeast Asia is updated with the inversion data from the Distributed Regional Aerosol Gridded Observation Networks (DRAGON)-northeast (NE) Asia campaign which was conducted during spring from March to May 2012. This updated aerosol model was then applied to a single visible channel algorithm to retrieve aerosol optical depth (AOD) from a Meteorological Imager (MI) on-board the geostationary meteorological satellite, Communication, Ocean, and Meteorological Satellite (COMS). This model plays an important role in retrieving accurate AOD from a single visible channel measurement. For the single-channel retrieval, sensitivity tests showed that perturbations by 4 % (0.926 +/- 0.04) in the assumed single scattering albedo (SSA) can result in the retrieval error in AOD by over 20 %. Since the measured reflectance at the top of the atmosphere depends on both AOD and SSA, the overestimation of assumed SSA in the aerosol model leads to an underestimation of AOD. Based on the AErosol RObotic NETwork (AERONET) inversion data sets obtained over East Asia before 2011, seasonally analyzed aerosol optical properties (AOPs) were categorized by SSAs at 675 nm of 0.92 +/- 0.035 for spring (March, April, and May). After the DRAGON-NE Asia campaign in 2012, the SSA during spring showed a slight increase to 0.93 +/- 0.035. In terms of the volume size distribution, the mode radius of coarse particles was increased from 2.08 +/- 0.40 to 2.14 +/- 0.40. While the original aerosol model consists of volume size distribution and refractive indices obtained before 2011, the new model is constructed by using a total data set after the DRAGON-NE Asia campaign. The large volume of data in high spatial resolution from this intensive campaign can be used to improve the representative aerosol model for East Asia. Accordingly, the new AOD data sets retrieved from a single-channel algorithm, which uses a precalculated look-up table (LUT) with the new aerosol model, show

  17. Iodine Satellite

    Science.gov (United States)

    Kamhawi, Hani; Dankanich, John; Martinez, Andres; Petro, Andrew

    2015-01-01

    The Iodine Satellite (iSat) spacecraft will be the first CubeSat to demonstrate high change in velocity from a primary propulsion system by using Hall thruster technology and iodine as a propellant. The mission will demonstrate CubeSat maneuverability, including plane change, altitude change and change in its closest approach to Earth to ensure atmospheric reentry in less than 90 days. The mission is planned for launch in fall 2017. Hall thruster technology is a type of electric propulsion. Electric propulsion uses electricity, typically from solar panels, to accelerate the propellant. Electric propulsion can accelerate propellant to 10 times higher velocities than traditional chemical propulsion systems, which significantly increases fuel efficiency. To enable the success of the propulsion subsystem, iSat will also demonstrate power management and thermal control capabilities well beyond the current state-of-the-art for spacecraft of its size. This technology is a viable primary propulsion system that can be used on small satellites ranging from about 22 pounds (10 kilograms) to more than 1,000 pounds (450 kilograms). iSat's fuel efficiency is ten times greater and its propulsion per volume is 100 times greater than current cold-gas systems and three times better than the same system operating on xenon. iSat's iodine propulsion system consists of a 200 watt (W) Hall thruster, a cathode, a tank to store solid iodine, a power processing unit (PPU) and the feed system to supply the iodine. This propulsion system is based on a 200 W Hall thruster developed by Busek Co. Inc., which was previously flown using xenon as the propellant. Several improvements have been made to the original system to include a compact PPU, targeting greater than 80 percent reduction in mass and volume of conventional PPU designs. The cathode technology is planned to enable heaterless cathode conditioning, significantly increasing total system efficiency. The feed system has been designed to

  18. Leucocytes, cytokines and satellite cells

    DEFF Research Database (Denmark)

    Paulsen, Gøran; Mikkelsen, Ulla Ramer; Raastad, Truls

    2012-01-01

    uncertain. The COX enzymes regulate satellite cell activity, as demonstrated in animal models; however the roles of the COX enzymes in human skeletal muscle need further investigation. We suggest using the term 'muscle damage' with care. Comparisons between studies and individuals must consider changes......-damaging exercise', primarily eccentric exercise. We review the evidence for the notion that the degree of muscle damage is related to the magnitude of the cytokine response. In the third and final section, we look at the satellite cell response to a single bout of eccentric exercise, as well as the role...... variation in individual responses to a given exercise should, however be expected. The link between cytokine and satellite cell responses and exercise-induced muscle damage is not so clear The systemic cytokine response may be linked more closely to the metabolic demands of exercise rather than muscle...

  19. Asteroid Satellites

    Science.gov (United States)

    Merline, W. J.

    2001-11-01

    Discovery and study of small satellites of asteroids or double asteroids can yield valuable information about the intrinsic properties of asteroids themselves and about their history and evolution. Determination of the orbits of these moons can provide precise masses of the primaries, and hence reliable estimates of the fundamental property of bulk density. This reveals much about the composition and structure of the primary and will allow us to make comparisons between, for example, asteroid taxonomic type and our inventory of meteorites. The nature and prevalence of these systems will also give clues as to the collisional environment in which they formed, and have further implications for the role of collisions in shaping our solar system. A decade ago, binary asteroids were more of a theoretical curiosity. In 1993, the Galileo spacecraft allowed the first undeniable detection of an asteroid moon, with the discovery of Dactyl, a small moon of Ida. Since that time, and particularly in the last year, the number of known binaries has risen dramatically. Previously odd-shaped and lobate near-Earth asteroids, observed by radar, have given way to signatures indicating, almost certainly, that at least four NEAs are binary systems. The tell-tale lightcurves of several other NEAs reveal a high likelihood of being double. Indications are that among the NEAs, there may be a binary frequency of several tens of percent. Among the main-belt asteroids, we now know of 6 confirmed binary systems, although their overall frequency is likely to be low, perhaps a few percent. The detections have largely come about because of significant advances in adaptive optics systems on large telescopes, which can now reduce the blurring of the Earth's atmosphere to compete with the spatial resolution of space-based imaging (which itself, via HST, is now contributing valuable observations). Most of these binary systems have similarities, but there are important exceptions. Searches among other

  20. Trends in communications satellites

    CERN Document Server

    Curtin, Denis J

    1979-01-01

    Trends in Communications Satellites offers a comprehensive look at trends and advances in satellite communications, including experimental ones such as NASA satellites and those jointly developed by France and Germany. The economic aspects of communications satellites are also examined. This book consists of 16 chapters and begins with a discussion on the fundamentals of electrical communications and their application to space communications, including spacecraft, earth stations, and orbit and wavelength utilization. The next section demonstrates how successful commercial satellite communicati

  1. Mobile satellite communications in the 1990's

    Science.gov (United States)

    Singh, Jai

    1992-07-01

    The evolution of Inmarsat global services from a single market and single service of the 1980's to all of the key mobile markets and a wide range of new terminals and services in the 1990's is described. An overview of existing mobile satellite services, as well as new services under implementation for introduction in the near and longer term, including a handheld satellite phone (Inmarsat-P), is provided. The initiative taken by Inmarsat in the integration of its global mobile satellite services with global navigation capability derived from GPS (Global Positioning System) and the GLONASS (Russian GPS) navigation satellite systems and the provision of an international civil overlay for GPS/GLONASS integrity and augmentation is highlighted. To complete the overview of the development of mobile satellite services in the 1990's, the known national and regional mobile satellite system plans and the various recent proposals for both orbiting and geostationary satellite systems for proving handheld satellite phone and/or data messaging services are described.

  2. An Alternative Inter-Satellite Calibration of the UMD HIRS OLR Retrievals

    Science.gov (United States)

    Robertson, Franklin R.; Lee, Hai-Tien

    2012-01-01

    Outgoing Longwave Radiation (OLR) at the top-of-atmosphere (TOA) is a fundamental component of Earth's energy balance and represents the heat energy in the thermal bands rejected to space by the planet. Determination of OLR from satellites has a long and storied history, but the observational record remains largely fragmented with gaps in satellite measurements over the past three decades. Perhaps the most semi-continuous set of retrievals comes from the University of Maryland (UMD) algorithm that uses four HIRS (High Resolution Infrared Sounder) channels on the NOAA polar orbiting satellites to estimate OLR. This data set shows great promise in helping to bridge the discontinuous ERBS (Earth Radiation Budget Satellite) and CERES (Clouds and the Earth s Radiant Energy System) measurements. However, significant satellite inter-calibration biases persist with the present UMD data, principally outside the tropics. Difficulties relate to the combination of drift of the satellite equator crossing time through the diurnal cycle and changes in HIRS channel response function design. Here we show how an ad hoc recalibration of the UMD retrievals among the different satellites removes much of the remaining uncertainty due to diurnal drift of the satellite orbit. The adjusted HIRS data (using no other external information) show much better agreement with OLR from the European Center Interim Reanalysis (EC-Int), longer-term signals in the Global Energy and Water Cycle Experiment / Surface Radiation Budget (GEWEX/SRB) retrievals, and also agree well with ERBS and CERES OLR measurements. These results augur well for narrowing the uncertainties in multi-decadal estimates of this important climate variable.

  3. Satellite image collection optimization

    Science.gov (United States)

    Martin, William

    2002-09-01

    Imaging satellite systems represent a high capital cost. Optimizing the collection of images is critical for both satisfying customer orders and building a sustainable satellite operations business. We describe the functions of an operational, multivariable, time dynamic optimization system that maximizes the daily collection of satellite images. A graphical user interface allows the operator to quickly see the results of what if adjustments to an image collection plan. Used for both long range planning and daily collection scheduling of Space Imaging's IKONOS satellite, the satellite control and tasking (SCT) software allows collection commands to be altered up to 10 min before upload to the satellite.

  4. Handbook of satellite applications

    CERN Document Server

    Madry, Scott; Camacho-Lara, Sergio

    2017-01-01

    The first edition of this ground breaking reference work was the most comprehensive reference source available about the key aspects of the satellite applications field. This updated second edition covers the technology, the markets, applications and regulations related to satellite telecommunications, broadcasting and networking—including civilian and military systems; precise satellite navigation and timing networks (i.e. GPS and others); remote sensing and meteorological satellite systems. Created under the auspices of the International Space University based in France, this brand new edition is now expanded to cover new innovative small satellite constellations, new commercial launching systems, innovation in military application satellites and their acquisition, updated appendices, a useful glossary and more.

  5. How Consistent are Recent Variations in the Tropical Energy and Water Cycle Resolved by Satellite Measurements?

    Science.gov (United States)

    Robertson, F. R.; Lu, H.-I.

    2004-01-01

    One notable aspect of Earth's climate is that although the planet appears to be very close to radiative balance at top-of-atmosphere (TOA), the atmosphere itself and underlying surface are not. Profound exchanges of energy between the atmosphere and oceans, land and cryosphere occur over a range of time scales. Recent evidence from broadband satellite measurements suggests that even these TOA fluxes contain some detectable variations. Our ability to measure and reconstruct radiative fluxes at the surface and at the top of atmosphere is improving rapidly. One question is 'How consistent, physically, are these diverse remotely-sensed data sets'? The answer is of crucial importance to understanding climate processes, improving physical models, and improving remote sensing algorithms. In this work we will evaluate two recently released estimates of radiative fluxes, focusing primarily on surface estimates. The International Satellite Cloud Climatology Project 'FD' radiative flux profiles are available from mid-1983 to near present and have been constructed by driving the radiative transfer physics from the Goddard Institute for Space Studies (GISS) global model with ISCCP clouds and TOVS (TIROS Operational Vertical Sounder)thermodynamic profiles. Full and clear sky SW and LW fluxes are produced. A similar product from the NASA/GEWEX Surface Radiation Budget Project using different radiative flux codes and thermodynamics from the NASA/Goddard Earth Observing System (GEOS-1) assimilation model makes a similar calculation of surface fluxes. However this data set currently extends only through 1995. We also employ precipitation measurements from the Global Precipitation Climatology Project (GPCP) and the Tropical Rainfall Measuring Mission (TRMM). Finally, ocean evaporation estimates from the Special Sensor Microwave Imager (SSM/I) are considered as well as derived evaporation from the NCAR/NCEP Reanalysis. Additional information is included in the original extended

  6. GPS Satellite Simulation Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The GPS satellite simulation facility consists of a GPS satellite simulator controlled by either a Silicon Graphics Origin 2000 or PC depending upon unit under test...

  7. Satellite switched FDMA advanced communication technology satellite program

    Science.gov (United States)

    Atwood, S.; Higton, G. H.; Wood, K.; Kline, A.; Furiga, A.; Rausch, M.; Jan, Y.

    1982-01-01

    The satellite switched frequency division multiple access system provided a detailed system architecture that supports a point to point communication system for long haul voice, video and data traffic between small Earth terminals at Ka band frequencies at 30/20 GHz. A detailed system design is presented for the space segment, small terminal/trunking segment at network control segment for domestic traffic model A or B, each totaling 3.8 Gb/s of small terminal traffic and 6.2 Gb/s trunk traffic. The small terminal traffic (3.8 Gb/s) is emphasized, for the satellite router portion of the system design, which is a composite of thousands of Earth stations with digital traffic ranging from a single 32 Kb/s CVSD voice channel to thousands of channels containing voice, video and data with a data rate as high as 33 Mb/s. The system design concept presented, effectively optimizes a unique frequency and channelization plan for both traffic models A and B with minimum reorganization of the satellite payload transponder subsystem hardware design. The unique zoning concept allows multiple beam antennas while maximizing multiple carrier frequency reuse. Detailed hardware design estimates for an FDMA router (part of the satellite transponder subsystem) indicate a weight and dc power budget of 353 lbs, 195 watts for traffic model A and 498 lbs, 244 watts for traffic model B.

  8. An access alternative for mobile satellite networks

    Science.gov (United States)

    Wu, W. W.

    1988-01-01

    Conceptually, this paper discusses strategies of digital satellite communication networks for a very large number of low density traffic stations. These stations can be either aeronautical, land mobile, or maritime. The techniques can be applied to international, domestic, regional, and special purpose satellite networks. The applications can be commercial, scientific, military, emergency, navigational or educational. The key strategy is the use of a non-orthogonal access method, which tolerates overlapping signals. With n being either time or frequency partitions, and with a single overlapping signal allowed, a low cost mobile satellite system can be designed with n squared (n squared + n + 1) number of terminals.

  9. Meteorological satellite systems

    CERN Document Server

    Tan, Su-Yin

    2014-01-01

    “Meteorological Satellite Systems” is a primer on weather satellites and their Earth applications. This book reviews historic developments and recent technological advancements in GEO and polar orbiting meteorological satellites. It explores the evolution of these remote sensing technologies and their capabilities to monitor short- and long-term changes in weather patterns in response to climate change. Satellites developed by various countries, such as U.S. meteorological satellites, EUMETSAT, and Russian, Chinese, Japanese and Indian satellite platforms are reviewed. This book also discusses international efforts to coordinate meteorological remote sensing data collection and sharing. This title provides a ready and quick reference for information about meteorological satellites. It serves as a useful tool for a broad audience that includes students, academics, private consultants, engineers, scientists, and teachers.

  10. Theory of geostationary satellites

    CERN Document Server

    Zee, Chong-Hung

    1989-01-01

    Geostationary or equatorial synchronous satellites are a daily reminder of our space efforts during the past two decades. The nightly television satellite weather picture, the intercontinental telecommunications of television transmissions and telephone conversations, and the establishrnent of educational programs in remote regions on Earth are constant reminders of the presence of these satellites. As used here, the term 'geo­ stationary' must be taken loosely because, in the long run, the satellites will not remain 'stationary' with respect to an Earth-fixed reference frame. This results from the fact that these satellites, as is true for all satellites, are incessantly subject to perturbations other than the central-body attraction of the Earth. Among the more predominant pertur­ bations are: the ellipticity of the Earth's equator, the Sun and Moon, and solar radiation pressure. Higher harmonics of the Earth's potential and tidal effects also influence satellite motion, but they are of second­ order whe...

  11. STABILITY OF SATELLITES IN CLOSELY PACKED PLANETARY SYSTEMS

    International Nuclear Information System (INIS)

    Payne, Matthew J.; Holman, Matthew J.; Deck, Katherine M.; Perets, Hagai B.

    2013-01-01

    We perform numerical integrations of four-body (star, planet, planet, satellite) systems to investigate the stability of satellites in planetary systems with tightly packed inner planets (STIPs). We find that the majority of closely spaced stable two-planet systems can stably support satellites across a range of parameter-space which is only slightly decreased compared to that seen for the single-planet case. In particular, circular prograde satellites remain stable out to ∼0.4 R H (where R H is the Hill radius) as opposed to 0.5 R H in the single-planet case. A similarly small restriction in the stable parameter-space for retrograde satellites is observed, where planetary close approaches in the range 2.5-4.5 mutual Hill radii destabilize most satellites orbits only if a ∼ 0.65 R H . In very close planetary pairs (e.g., the 12:11 resonance) the addition of a satellite frequently destabilizes the entire system, causing extreme close approaches and the loss of satellites over a range of circumplanetary semi-major axes. The majority of systems investigated stably harbored satellites over a wide parameter-space, suggesting that STIPs can generally offer a dynamically stable home for satellites, albeit with a slightly smaller stable parameter-space than the single-planet case. As we demonstrate that multi-planet systems are not a priori poor candidates for hosting satellites, future measurements of satellite occurrence rates in multi-planet systems versus single-planet systems could be used to constrain either satellite formation or past periods of strong dynamical interaction between planets

  12. Tracking and data relay satellite system (TDRSS) capabilities

    Science.gov (United States)

    Spearing, R. E.

    1985-10-01

    The Tracking and Data Relay Satellite System (TDRSS) is the latest implementation to tracking and data acquisition network for near-earth orbiting satellite support designed to meet the requirements of the current and projected (to the year 2000) satellite user community. The TDRSS consists of a space segment (SS) and a ground segment (GS) that fit within NASA's Space Network (SN) complex controlled at the Goddard Space Flight Center. The SS currently employs a single satellite, TDRS-1, with two additional satellites to be deployed in January 1986 and July 1986. The GS contains the communications and equipment required to manage the three TDR satellites and to transmit and receive information to and from TDRSS user satellites. Diagrams and tables illustrating the TDRSS signal characteristics, the situation of TDRSS within the SN, the SN operations and element interrelationships, as well as future plans for new missions are included.

  13. Isolation, Culture, Functional Assays, and Immunofluorescence of Myofiber-Associated Satellite Cells.

    Science.gov (United States)

    Vogler, Thomas O; Gadek, Katherine E; Cadwallader, Adam B; Elston, Tiffany L; Olwin, Bradley B

    2016-01-01

    Adult skeletal muscle stem cells, termed satellite cells, regenerate and repair the functional contractile cells in adult skeletal muscle called myofibers. Satellite cells reside in a niche between the basal lamina and sarcolemma of myofibers. Isolating single myofibers and their associated satellite cells provides a culture system that partially mimics the in vivo environment. We describe methods for isolating and culturing intact individual myofibers and their associated satellite cells from the mouse extensor digitorum longus muscle. Following dissection and isolation of individual myofibers we provide protocols for myofiber transplantation, satellite cell transfection, immune detection of satellite cell antigens, and assays to examine satellite cell self-renewal and proliferation.

  14. Communication satellite applications

    Science.gov (United States)

    Pelton, Joseph N.

    The status and future of the technologies, numbers and services provided by communications satellites worldwide are explored. The evolution of Intelsat satellites and the associated earth terminals toward high-rate all-digital telephony, data, facsimile, videophone, videoconferencing and DBS capabilities are described. The capabilities, services and usage of the Intersputnik, Eutelsat, Arabsat and Palapa systems are also outlined. Domestic satellite communications by means of the Molniya, ANIK, Olympus, Intelsat and Palapa spacecraft are outlined, noting the fast growth of the market and the growing number of different satellite manufacturers. The technical, economic and service definition issues surrounding DBS systems are discussed, along with presently operating and planned maritime and aeronautical communications and positioning systems. Features of search and rescue and tracking, data, and relay satellite systems are summarized, and services offered or which will be offered by every existing or planned communication satellite worldwide are tabulated.

  15. Implementation of Multiple Access Techniques Applicable for Maritime Satellite Communications

    OpenAIRE

    Stojce Dimov Ilcev

    2013-01-01

    In this paper are introduced fundamentals, characteristics, advantages and disadvantages of Multiple Access (MA) employed as transmission techniques in the Maritime Mobile Satellite Communications (MMSC) between ships and Coast Earth Station (CES) via Geostationary Earth Orbit (GEO) or Not-GEO satellite constellations. In fixed satellite communication, as a rule, especially in MMSC many users are active at the same time. The problem of simultaneous communications between many single or multip...

  16. Satellite services system overview

    Science.gov (United States)

    Rysavy, G.

    1982-01-01

    The benefits of a satellite services system and the basic needs of the Space Transportation System to have improved satellite service capability are identified. Specific required servicing equipment are discussed in terms of their technology development status and their operative functions. Concepts include maneuverable television systems, extravehicular maneuvering unit, orbiter exterior lighting, satellite holding and positioning aid, fluid transfer equipment, end effectors for the remote manipulator system, teleoperator maneuvering system, and hand and power tools.

  17. Configurable software for satellite graphics

    Energy Technology Data Exchange (ETDEWEB)

    Hartzman, P D

    1977-12-01

    An important goal in interactive computer graphics is to provide users with both quick system responses for basic graphics functions and enough computing power for complex calculations. One solution is to have a distributed graphics system in which a minicomputer and a powerful large computer share the work. The most versatile type of distributed system is an intelligent satellite system in which the minicomputer is programmable by the application user and can do most of the work while the large remote machine is used for difficult computations. At New York University, the hardware was configured from available equipment. The level of system intelligence resulted almost completely from software development. Unlike previous work with intelligent satellites, the resulting system had system control centered in the satellite. It also had the ability to reconfigure software during realtime operation. The design of the system was done at a very high level using set theoretic language. The specification clearly illustrated processor boundaries and interfaces. The high-level specification also produced a compact, machine-independent virtual graphics data structure for picture representation. The software was written in a systems implementation language; thus, only one set of programs was needed for both machines. A user can program both machines in a single language. Tests of the system with an application program indicate that is has very high potential. A major result of this work is the demonstration that a gigantic investment in new hardware is not necessary for computing facilities interested in graphics.

  18. Function of Junk: Pericentromeric Satellite DNA in Chromosome Maintenance.

    Science.gov (United States)

    Jagannathan, Madhav; Yamashita, Yukiko M

    2018-04-02

    Satellite DNAs are simple tandem repeats that exist at centromeric and pericentromeric regions on eukaryotic chromosomes. Unlike the centromeric satellite DNA that comprises the vast majority of natural centromeres, function(s) for the much more abundant pericentromeric satellite repeats are poorly understood. In fact, the lack of coding potential allied with rapid divergence of repeat sequences across eukaryotes has led to their dismissal as "junk DNA" or "selfish parasites." Although implicated in various biological processes, a conserved function for pericentromeric satellite DNA remains unidentified. We have addressed the role of satellite DNA through studying chromocenters, a cytological aggregation of pericentromeric satellite DNA from multiple chromosomes into DNA-dense nuclear foci. We have shown that multivalent satellite DNA-binding proteins cross-link pericentromeric satellite DNA on chromosomes into chromocenters. Disruption of chromocenters results in the formation of micronuclei, which arise by budding off the nucleus during interphase. We propose a model that satellite DNAs are critical chromosome elements that are recognized by satellite DNA-binding proteins and incorporated into chromocenters. We suggest that chromocenters function to preserve the entire chromosomal complement in a single nucleus, a fundamental and unquestioned feature of eukaryotic genomes. We speculate that the rapid divergence of satellite DNA sequences between closely related species results in discordant chromocenter function and may underlie speciation and hybrid incompatibility. © 2017 Jagannathan and Yamashita; Published by Cold Spring Harbor Laboratory Press.

  19. Satellite Communications Industry

    Science.gov (United States)

    1993-04-01

    Ariane $loom SAJAC 1 Hughes Satellite Japan 06/94 $150m SAJAC 2 Hughes Satellite Japan -- (spare) $150m SatcomHl GE GE Americom /95 $50m SOLIDARIDAD ...1 Hughes SCT (Mexico) 11/93 Ariane $loom SOLIDARIDAD 2 Hughes SCT (Mexico) /94 $loom Superbird Al Loral Space Com Gp (Jap) 11/92 Ariane $175m

  20. Partnership via Satellite.

    Science.gov (United States)

    Powell, Marie Clare

    1980-01-01

    Segments of the 1980 National Catholic Educational Association (NCEA) conference were to be telecast nationally by satellite. The author briefly explains the satellite transmission process and advises Catholic educators on how to pick up the broadcast through their local cable television system. (SJL)

  1. The satellite situation center

    International Nuclear Information System (INIS)

    Teague, M.J.; Sawyer, D.M.; Vette, J.I.

    1982-01-01

    Considerations related to the early planning for the International Magnetospheric Study (IMS) took into account the desirability of an establishment of specific entities for generating and disseminating coordination information for both retrospective and predictive periods. The organizations established include the IMS/Satellite Situation Center (IMS/SSC) operated by NASA. The activities of the SSC are related to the preparation of reports on predicted and actually achieved satellite positions, the response to inquiries, the compilation of information on satellite experiments, and the issue of periodic status summaries. Attention is given to high-altitude satellite services, other correlative satellite services, non-IMS activities of the SSC, a summary of the SSC request activity, and post-IMS and future activities

  2. Advanced domestic digital satellite communications systems experiments

    Science.gov (United States)

    Iso, A.; Izumisawa, T.; Ishida, N.

    1984-02-01

    The characteristics of advanced digital transmission systems were measured, using newly developed small earth stations and a K-band and C-band communication satellite. Satellite link performance for data, facsimile, video and packet switching information transmission at bit rates ranging from 6.4 kbit/s to 6.3 Mbit/s have been confirmed, using a small K-band earth station and a demand-assignment time division multiple access system. A low-capacity omni-use C-band terminal experiment has verified a telephone channel transmission performance by spread-spectrum multiple access. Single point to multipoint transmission characteristics of the 64 kbit/s data signals from the computer center were tested, using a receive-only 4 GHz earth terminal. Basic satellite link performance was confirmed under clear-sky conditions. Precise satellite orbit and attitude keeping experiments were carried out to obtain precise satellite antenna pointing accuracy for development of K-band earth stations that do not require satellite tracking equipment. Precise station keeping accuracy of 0.02 degrees was obtained.

  3. Enterprise Level Status and Control of Multi-Satellite Operations

    Data.gov (United States)

    National Aeronautics and Space Administration — Single-satellite mission operation centers are used for nearly all Goddard Space Flight Center (GSFC) mission ground data systems, with a focus on localized data...

  4. Web Transfer Over Satellites Being Improved

    Science.gov (United States)

    Allman, Mark

    1999-01-01

    Extensive research conducted by NASA Lewis Research Center's Satellite Networks and Architectures Branch and the Ohio University has demonstrated performance improvements in World Wide Web transfers over satellite-based networks. The use of a new version of the Hypertext Transfer Protocol (HTTP) reduced the time required to load web pages over a single Transmission Control Protocol (TCP) connection traversing a satellite channel. However, an older technique of simultaneously making multiple requests of a given server has been shown to provide even faster transfer time. Unfortunately, the use of multiple simultaneous requests has been shown to be harmful to the network in general. Therefore, we are developing new mechanisms for the HTTP protocol which may allow a single request at any given time to perform as well as, or better than, multiple simultaneous requests. In the course of study, we also demonstrated that the time for web pages to load is at least as short via a satellite link as it is via a standard 28.8-kbps dialup modem channel. This demonstrates that satellites are a viable means of accessing the Internet.

  5. Virtual Satellite Construction and Application for Image Classification

    International Nuclear Information System (INIS)

    Su, W G; Su, F Z; Zhou, C H

    2014-01-01

    Nowadays, most remote sensing image classification uses single satellite remote sensing data, so the number of bands and band spectral width is consistent. In addition, observed phenomenon such as land cover have the same spectral signature, which causes the classification accuracy to decrease as different data have unique characteristic. Therefore, this paper analyzes different optical remote sensing satellites, comparing the spectral differences and proposes the ideas and methods to build a virtual satellite. This article illustrates the research on the TM, HJ-1 and MODIS data. We obtained the virtual band X 0 through these satellites' bands combined it with the 4 bands of a TM image to build a virtual satellite with five bands. Based on this, we used these data for image classification. The experimental results showed that the virtual satellite classification results of building land and water information were superior to the HJ-1 and TM data respectively

  6. Probability of satellite collision

    Science.gov (United States)

    Mccarter, J. W.

    1972-01-01

    A method is presented for computing the probability of a collision between a particular artificial earth satellite and any one of the total population of earth satellites. The collision hazard incurred by the proposed modular Space Station is assessed using the technique presented. The results of a parametric study to determine what type of satellite orbits produce the greatest contribution to the total collision probability are presented. Collision probability for the Space Station is given as a function of Space Station altitude and inclination. Collision probability was also parameterized over miss distance and mission duration.

  7. Effects of 3-D clouds on atmospheric transmission of solar radiation: Cloud type dependencies inferred from A-train satellite data

    Science.gov (United States)

    Ham, Seung-Hee; Kato, Seiji; Barker, Howard W.; Rose, Fred G.; Sun-Mack, Sunny

    2014-01-01

    Three-dimensional (3-D) effects on broadband shortwave top of atmosphere (TOA) nadir radiance, atmospheric absorption, and surface irradiance are examined using 3-D cloud fields obtained from one hour's worth of A-train satellite observations and one-dimensional (1-D) independent column approximation (ICA) and full 3-D radiative transfer simulations. The 3-D minus ICA differences in TOA nadir radiance multiplied by π, atmospheric absorption, and surface downwelling irradiance, denoted as πΔI, ΔA, and ΔT, respectively, are analyzed by cloud type. At the 1 km pixel scale, πΔI, ΔA, and ΔT exhibit poor spatial correlation. Once averaged with a moving window, however, better linear relationships among πΔI, ΔA, and ΔT emerge, especially for moving windows larger than 5 km and large θ0. While cloud properties and solar geometry are shown to influence the relationships amongst πΔI, ΔA, and ΔT, once they are separated by cloud type, their linear relationships become much stronger. This suggests that ICA biases in surface irradiance and atmospheric absorption can be approximated based on ICA biases in nadir radiance as a function of cloud type.

  8. OLFAR, a radio telescope based on nano satellites in moon orbit

    NARCIS (Netherlands)

    Engelen, S.; Verhoeven, C.J.M.; Bentum, Marinus Jan

    2010-01-01

    It seems very likely that missions with nano-satellites in professional scientific or commercial applications will not be single-satellite missions. Well structured formations or less structured swarms of nano-satellites will be able to perform tasks that cannot be done in the “traditional‿ way. The

  9. Satellite broadcasting - The European experience and perspective

    Science.gov (United States)

    Watson, Alan

    1991-11-01

    The use of satellites is considered as a means for developing a European transnational broadcasting system with attention given to the control of technology. A tension is described between maintaining technology as the property of one nation when the DBSs are developed for multinational program broadcasting. The simultaneous development of satellite systems is theorized to lead eventually to a single merged program for a particular nation, and the effect is considered of the regulation of cross-holding and cross-selling systems by investors.

  10. Beware the single hit!

    CERN Multimedia

    2008-01-01

    The first time that single particle effects from cosmic rays on electronics were observed was in 1991, when one of the instruments aboard an ESA satellite broke down after only five days in space. On 5 July, the TS-LEA group will have completed the installation of monitors that will help to reduce similar dangerous effects on LHC electronics.

  11. Advanced mobile satellite communications system using Ka and MM-wave bands in Japan's R and D satellite project

    Science.gov (United States)

    Isobe, Shunkichi; Ohmori, Shingo; Hamamoto, Naokazu; Yamamoto, Minoru

    1991-01-01

    Communications Research Laboratory (CRL) studied an advanced mobile satellite communications system using Ka and millimeter-wave bands in the R&D Satellite project. The project started in 1990 and the satellite will be launched in 1997. On-board multi-beam interconnecting is one of basic functions to realize one-hop connection among Very Small Aperture Terminals (VSATs), mobile, and hand-held terminals in future mobile satellite communications system. An Intermediate Frequency (IF) filter bank and regenerative transponder are suitable for this function. The transponder configuration of an advanced mobile communications mission of the R&D Satellite for experiment is shown. High power transmitters of Ka and millimeter-wave bands, a 3x3 IF filter band and Single Channel Per Carrier/Time Division Multiplexing (SCPC/TDM) regenerative MODEMS, which will be boarded on the R&D Satellite, are being developed for the purpose of studying the feasibility of advanced mobile communications system.

  12. DS-CDMA satellite diversity reception for personal satellite communication: Downlink performance analysis

    Science.gov (United States)

    DeGaudenzi, Riccardo; Giannetti, Filippo

    1995-01-01

    The downlink of a satellite-mobile personal communication system employing power-controlled Direct Sequence Code Division Multiple Access (DS-CDMA) and exploiting satellite-diversity is analyzed and its performance compared with a more traditional communication system utilizing single satellite reception. The analytical model developed has been thoroughly validated by means of extensive Monte Carlo computer simulations. It is shown how the capacity gain provided by diversity reception shrinks considerably in the presence of increasing traffic or in the case of light shadowing conditions. Moreover, the quantitative results tend to indicate that to combat system capacity reduction due to intra-system interference, no more than two satellites shall be active over the same region. To achieve higher system capacity, differently from terrestrial cellular systems, Multi-User Detection (MUD) techniques are likely to be required in the mobile user terminal, thus considerably increasing its complexity.

  13. Handbook of satellite applications

    CERN Document Server

    Madry, Scott; Camacho-Lara, Sergio

    2013-01-01

    Top space experts from around the world have collaborated to produce this comprehensive, authoritative, and clearly illustrated reference guide to the fast growing, multi-billion dollar field of satellite applications and space communications. This handbook, done under the auspices of the International Space University based in France, addresses not only system technologies but also examines market dynamics, technical standards and regulatory constraints. The handbook is a completely multi-disciplinary reference book that covers, in an in-depth fashion, the fields of satellite telecommunications, Earth observation, remote sensing, satellite navigation, geographical information systems, and geosynchronous meteorological systems. It covers current practices and designs as well as advanced concepts and future systems. It provides a comparative analysis of the common technologies and design elements for satellite application bus structures, thermal controls, power systems, stabilization techniques, telemetry, com...

  14. Domestic Communication Satellites

    Science.gov (United States)

    Horowitz, Andrew

    1974-01-01

    A discussion of the Federal Communications Commission's new policy on domestic satellites in light of our 1) military and economic history; 2) corporate interests; 3) citizen surveillance; and 4) media control. (HB)

  15. SATELLITE CONSTELLATION DESIGN PARAMETER

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. SATELLITE CONSTELLATION DESIGN PARAMETER. 1. ORBIT CHARACTERISTICS. ORBITAL HEIGHT >= 20,000 KM. LONGER VISIBILITY; ORBITAL PERIOD. PERTURBATIONS(MINIMUM). SOLAR RADIATION PRESSURE (IMPACTS ECCENTRICITY); LUNI ...

  16. Satellite Communications for ATM

    Science.gov (United States)

    Shamma, Mohammed A.

    2003-01-01

    This presentation is an overview on Satellite Communication for the Aeronautical Telecommunication Management (ATM) research. Satellite Communications are being considered by the FAA and NASA as a possible alternative to the present and future ground systems supporting Air Traffic Communications. The international Civil Aviation Organization (ICAO) have in place Standards and Recommended Practices (SARPS) for the Aeronautical Mobile Satellite Services (AMSS) which is mainly derived from the pre-existing Inmarsat service that has been in service since the 1980s. The Working Group A of the Aeronautical Mobile Communication Panel of ICAO has also been investigating SARPS for what is called the Next Generation Satellite Service (NGSS) which conforms less to the Inmarsat based architecture and explores wider options in terms of satellite architectures. Several designs are being proposed by Firms such as Boeing, ESA, NASA that are geared toward full or secondary usage of satellite communications for ATM. Satellite communications for ATM can serve several purposes ranging from primary usage where ground services would play a minimal backup role, to an integrated solution where it will be used to cover services, or areas that are less likely to be supported by the proposed and existing ground infrastructure. Such Integrated roles can include usage of satellite communications for oceanic and remote land areas for example. It also can include relieving the capacity of the ground network by providing broadcast based services of Traffic Information Services messages (TIS-B), or Flight Information Services (FIS-B) which can take a significant portion of the ground system capacity. Additionally, satellite communication can play a backup role to support any needs for ground replacement, or additional needed capacity even after the new digital systems are in place. The additional bandwidth that can be provided via satellite communications can also open the door for many new

  17. Sensing single electrons with single molecules

    International Nuclear Information System (INIS)

    Plakhotnik, Taras

    2007-01-01

    We propose a new methodology for probing transport of just one electron, a process of great importance both in nature and in artificial devices. Our idea for locating a single electron is analogues to the conventional GPS where signals from several satellites are used to locate a macro object. Using fluorescent molecules as tiny sensors, it is possible to determine 3D displacement vector of an electron

  18. Satellite remote sensing of Asian aerosols: a case study of clean, polluted, and Asian dust storm days

    Directory of Open Access Journals (Sweden)

    K. H. Lee

    2010-12-01

    Full Text Available In East Asia, satellite observation is important because aerosols from natural and anthropogenic sources have been recognized as a major source of regional and global air pollution. However, retrieving aerosols properties from satellite observations over land can be difficult because of the surface reflection, complex aerosol composition, and aerosol absorption. In this study, a new aerosol retrieval method called as the Moderate Resolution Imaging Spectroradiometer (MODIS satellite aerosol retrieval (MSTAR was developed and applied to three different aerosol event cases over East Asia. MSTAR uses a separation technique that can distinguish aerosol reflectance from top-of-atmosphere (TOA reflectance. The aerosol optical thickness (AOT was determined by comparing this aerosol reflectance with pre-calculated values. Three case studies show how the methodology identifies discrepancies between measured and calculated values to retrieve more accurate AOT. The comparison between MODIS and the Aerosol Robotic Network (AERONET showed improvement using the suggested methodology with the cluster-based look-up-tables (LUTs (linear slope = 0.94, R = 0.92 than using operational MODIS collection 5 aerosol products (linear slope = 0.78, R = 0.87. In conclusion, the suggested methodology is shown to work well with aerosol models acquired by statistical clustering of the observation data in East Asia.

  19. Hydrocarbons on Saturn's satellites Iapetus and Phoebe

    Science.gov (United States)

    Cruikshank, D.P.; Wegryn, E.; Dalle, Ore C.M.; Brown, R.H.; Bibring, J.-P.; Buratti, B.J.; Clark, R.N.; McCord, T.B.; Nicholson, P.D.; Pendleton, Y.J.; Owen, T.C.; Filacchione, G.; Coradini, A.; Cerroni, P.; Capaccioni, F.; Jaumann, R.; Nelson, R.M.; Baines, K.H.; Sotin, Christophe; Bellucci, G.; Combes, M.; Langevin, Y.; Sicardy, B.; Matson, D.L.; Formisano, V.; Drossart, P.; Mennella, V.

    2008-01-01

    Material of low geometric albedo (pV ??? 0.1) is found on many objects in the outer Solar System, but its distribution in the saturnian satellite system is of special interest because of its juxtaposition with high-albedo ice. In the absence of clear, diagnostic spectral features, the composition of this low-albedo (or "dark") material is generally inferred to be carbon-rich, but the form(s) of the carbon is unknown. Near-infrared spectra of the low-albedo hemisphere of Saturn's satellite Iapetus were obtained with the Visible-Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft at the fly-by of that satellite of 31 December 2004, yielding a maximum spatial resolution on the satellite's surface of ???65 km. The spectral region 3-3.6 ??m reveals a broad absorption band, centered at 3.29 ??m, and concentrated in a region comprising about 15% of the low-albedo surface area. This is identified as the C{single bond}H stretching mode vibration in polycyclic aromatic hydrocarbon (PAH) molecules. Two weaker bands attributed to {single bond}CH2{single bond} stretching modes in aliphatic hydrocarbons are found in association with the aromatic band. The bands most likely arise from aromatic and aliphatic units in complex macromolecular carbonaceous material with a kerogen- or coal-like structure, similar to that in carbonaceous meteorites. VIMS spectra of Phoebe, encountered by Cassini on 11 June 2004, also show the aromatic hydrocarbon band, although somewhat weaker than on Iapetus. The origin of the PAH molecular material on these two satellites is unknown, but PAHs are found in carbonaceous meteorites, cometary dust particles, circumstellar dust, and interstellar dust. ?? 2007 Elsevier Inc. All rights reserved.

  20. Satellite monitoring of cyanobacterial harmful algal bloom ...

    Science.gov (United States)

    Cyanobacterial harmful algal blooms (cyanoHABs) cause extensive problems in lakes worldwide, including human and ecological health risks, anoxia and fish kills, and taste and odor problems. CyanoHABs are a particular concern because of their dense biomass and the risk of exposure to toxins in both recreational waters and drinking source waters. Successful cyanoHAB assessment by satellites may provide a first-line of defense indicator for human and ecological health protection. In this study, assessment methods were developed to determine the utility of satellite technology for detecting cyanoHAB occurrence frequency at locations of potential management interest. The European Space Agency's MEdium Resolution Imaging Spectrometer (MERIS) was evaluated to prepare for the equivalent Sentinel-3 Ocean and Land Colour Imager (OLCI) launched in 2016. Based on the 2012 National Lakes Assessment site evaluation guidelines and National Hydrography Dataset, there were 275,897 lakes and reservoirs greater than 1 hectare in the 48 U.S. states. Results from this evaluation show that 5.6 % of waterbodies were resolvable by satellites with 300 m single pixel resolution and 0.7 % of waterbodies were resolvable when a 3x3 pixel array was applied based on minimum Euclidian distance from shore. Satellite data was also spatially joined to US public water surface intake (PWSI) locations, where single pixel resolution resolved 57% of PWSI and a 3x3 pixel array resolved 33% of

  1. Satellite failures revisited

    Science.gov (United States)

    Balcerak, Ernie

    2012-12-01

    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.

  2. ESA's satellite communications programme

    Science.gov (United States)

    Bartholome, P.

    1985-02-01

    The developmental history, current status, and future plans of the ESA satellite-communications programs are discussed in a general survey and illustrated with network diagrams and maps. Consideration is given to the parallel development of national and European direct-broadcast systems and telecommunications networks, the position of the European space and electronics industries in the growing world market, the impact of technological improvements (both in satellite systems and in ground-based networks), and the technological and commercial advantages of integrated space-terrestrial networks. The needs for a European definition of the precise national and international roles of satellite communications, for maximum speed in implementing such decisions (before the technology becomes obsolete), and for increased cooperation and standardization to assure European equipment manufacturers a reasonable share of the market are stressed.

  3. Solar Power Satellites

    CERN Document Server

    Flournoy, Don M

    2012-01-01

    Communication satellites are a $144 billion industry. Is there any space-based industry that could possibly beat that market? 'Solar Power Satellites' shows why and how the space satellite industry will soon begin expanding its market from relaying signals to Earth to generating energy in space and delivering it to the ground as electricity. In all industrialized nations, energy demand is growing exponentially. In the developing world, the need for energy is as basic as food and water. The Sun's energy is available everywhere, and it is non-polluting. As business plans demonstrate its technical feasibility, commercial potential, and environmental acceptability, every country on Earth will look to space for the power it needs.

  4. Geostationary satellites collocation

    CERN Document Server

    Li, Hengnian

    2014-01-01

    Geostationary Satellites Collocation aims to find solutions for deploying a safe and reliable collocation control. Focusing on the orbital perturbation analysis, the mathematical foundations for orbit and control of the geostationary satellite are summarized. The mathematical and physical principle of orbital maneuver and collocation strategies for multi geostationary satellites sharing with the same dead band is also stressed. Moreover, the book presents some applications using the above algorithms and mathematical models to help readers master the corrective method for planning station keeping maneuvers. Engineers and scientists in the fields of aerospace technology and space science can benefit from this book. Hengnian Li is the Deputy Director of State Key Laboratory of Astronautic Dynamics, China.

  5. Exobiology of icy satellites

    Science.gov (United States)

    Simakov, M. B.

    At the beginning of 2004 the total number of discovered planets near other stars was 119 All of them are massive giants and met practically in all orbits In a habitable zone from 0 8 up to 1 1 AU at less 11 planets has been found starting with HD 134987 and up to HD 4203 It would be naive to suppose existence of life in unique known to us amino-nucleic acid form on the gas-liquid giant planets Nevertheless conditions for onset and evolutions of life can be realized on hypothetical satellites extrasolar planets All giant planets of the Solar system have a big number of satellites 61 of Jupiter 52 of Saturn known in 2003 A small part of them consist very large bodies quite comparable to planets of terrestrial type but including very significant share of water ice Some from them have an atmosphere E g the mass of a column of the Titan s atmosphere exceeds 15 times the mass of the Earth atmosphere column Formation or capture of satellites is a natural phenomenon and satellite systems definitely should exist at extrasolar planets A hypothetical satellite of the planet HD 28185 with a dense enough atmosphere and hydrosphere could have biosphere of terrestrial type within the limits of our notion about an origin of terrestrial biosphere As an example we can see on Titan the largest satellite of Saturn which has a dense nitrogen atmosphere and a large quantity of liquid water under ice cover and so has a great exobiological significance The most recent models of the Titan s interior lead to the conclusion that a substantial liquid layer

  6. GPS satellite surveying

    CERN Document Server

    Leick, Alfred; Tatarnikov, Dmitry

    2015-01-01

    THE MOST COMPREHENSIVE, UP-TO-DATE GUIDE ON GPS TECHNOLOGY FOR SURVEYING Three previous editions have established GPS Satellite Surveying as the definitive industry reference. Now fully updated and expanded to reflect the newest developments in the field, this Fourth Edition features cutting-edge information on GNSS antennas, precise point positioning, real-time relative positioning, lattice reduction, and much more. Expert authors examine additional tools and applications, offering complete coverage of geodetic surveying using satellite technologies. The past decade has seen a major evolut

  7. JPSS Preparations at the Satellite Proving Ground for Marine, Precipitation, and Satellite Analysis

    Science.gov (United States)

    Folmer, M. J.; Berndt, E.; Clark, J.; Orrison, A.; Kibler, J.; Sienkiewicz, J. M.; Nelson, J. A., Jr.; Goldberg, M.

    2016-12-01

    The National Oceanic and Atmospheric Administration (NOAA) Satellite Proving Ground (PG) for Marine, Precipitation, and Satellite Analysis (MPS) has been demonstrating and evaluating Suomi National Polar-orbiting Partnership (S-NPP) products along with other polar-orbiting satellite platforms in preparation for the Joint Polar Satellite System - 1 (JPSS-1) launch in March 2017. The first S-NPP imagery was made available to the MPS PG during the evolution of Hurricane Sandy in October 2012 and has since been popular in operations. Since this event the MPS PG Satellite Liaison has been working with forecasters on ways to integrate single-channel and multispectral imagery from the Visible Infrared Imaging Radiometer Suite (VIIRS), the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Advanced Very High Resolution Radiometer (AVHRR)into operations to complement numerical weather prediction and geostationary satellite savvy National Weather Service (NWS) National Centers. Additional unique products have been introduced to operations to address specific forecast challenges, including the Cooperative Institute for Research in the Atmosphere (CIRA) Layered Precipitable Water, the National Environmental Satellite, Data, and Information Service (NESDIS) Snowfall Rate product, NOAA Unique Combined Atmospheric Processing System (NUCAPS) Soundings, ozone products from the Atmospheric Infrared Sounder (AIRS), Cross-track Infrared Sounder/Advanced Technology Microwave Sounder (CrIS/ATMS), and Infrared Atmospheric Sounding Interferometer (IASI). In addition, new satellite domains have been created to provide forecasters at the NWS Ocean Prediction Center and Weather Prediction Center with better quality imagery at high latitudes. This has led to research projects that are addressing forecast challenges such as tropical to extratropical transition and explosive cyclogenesis. This presentation will provide examples of how the MPS PG has been introducing and integrating

  8. Satellite Contributions to Global Change Studies

    Science.gov (United States)

    Parkinson, Claire L.

    2009-01-01

    By providing a global view with a level playing field (no region missed because of unfavorable surface conditions or political boundaries), satellites have made major contributions to improved monitoring and understanding of our constantly changing planet. The global view has allowed surprising realizations like the relative sparsity of lightning strikes over oceans and the large-scale undulations on the massive Antarctic ice sheet. It has allowed the tracking of all sorts of phenomena, including aerosols, both natural and anthropogenic, as they move with the atmospheric circulation and impact weather and human health. But probably nothing that the global view allows is more important in the long term than its provision. of unbiased data sets to address the issue of global change, considered by many to be among the most important issues facing humankind today. With satellites we can monitor atmospheric temperatures at all latitudes and longitudes, and obtain a global average that lessens the likelihood of becoming endlessly mired in the confusions brought about by the certainty of regional differences. With satellites we can monitor greenhouse gases such as CO2 not just above individual research stations but around the globe. With satellites we can monitor the polar sea ice covers, as we have done since the late 1970s, determining and quantifying the significant reduction in Arctic sea ice and the slight growth in Antarctic sea ice over that period, With satellites we can map the full extent and changes in the Antarctic stratospheric ozone depletions that were first identified from using a single ground station; and through satellite data we have witnessed from afar land surface changes brought about by humans both intentionally, as with wide-scale deforestation, and unintentionally, as with the decay of the Aral Sea. The satellite data are far from sufficient for all that we need in order to understand the global system and forecast its changes, as we also need

  9. The American Satellite Company (ASC) satellite deployed from payload bay

    Science.gov (United States)

    1985-01-01

    The American Satellite Company (ASC) communications satellite is deployed from the payload bay of the Shuttle Discovery. A portion of the cloudy surface of the earth can be seen to the left of the frame.

  10. Leveraging the NPS Femto Satellite for Alternative Satellite Communication Networks

    Science.gov (United States)

    2017-09-01

    programmed for eventual integration with the Iridium Network , which is then tested. C. THESIS ORGANIZATION The thesis addresses these questions...NPS FEMTO SATELLITE FOR ALTERNATIVE SATELLITE COMMUNICATION NETWORKS by Faisal S. Alshaya September 2017 Co-Advisors: Steven J. Iatrou...TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE LEVERAGING THE NPS FEMTO SATELLITE FOR ALTERNATIVE SATELLITE COMMUNICATION NETWORKS 5

  11. Satellite Surveillance: Domestic Issues

    National Research Council Canada - National Science Library

    Best, Jr., Richard A; Elsea, Jennifer K

    2008-01-01

    ... and law enforcement purposes, in addition to the civil applications that have been supported for years. In 2007, it moved to transfer responsibility for coordinating civilian use of satellites to the Department of Homeland Security. The transfer occurred, however, apparently without notification of key congressional oversight committees.

  12. Cibola flight experiment satellite

    Science.gov (United States)

    Davies, P.; Liddle, Doug; Paffett, John; Sweeting, Martin; Curiel, A.; Sun, Wei; Eves, Stuart

    2004-11-01

    In order to achieve an "economy of scale" with respect to payload capacity the major trend in telecommunications satellites is for larger and larger platforms. With these large platforms the level of integration between platform and payload is increasing leading to longer delivery schedules. The typical lifecycle for procurement of these large telecommunications satellites is now 3-6 years depending on the level of non-recurring engineering needed. Surrey Satellite Technology Ltd (SSTL) has designed a low-cost platform aimed at telecommunications and navigation applications. SSTL's Geostationary Minisatellite Platform (GMP) is a new entrant addressing the lower end of the market with payloads up to 250kg requiring less than 1.5 kW power. The British National Space Centre through the MOSAIC Small Satellite Initiative supported the development of GMP. The main design goals for GMP are low-cost for the complete mission including launch and operations and a platform allowing flexible payload accommodation. GMP is specifically designed to allow rapid development and deployment with schedules typically between 1 and 2 years from contract signature to flight readiness. GMP achieves these aims by a modular design where the level of integration between the platform and payload is low. The modular design decomposes the satellite into three major components - the propulsion bay, the avionics bay and the payload module. Both the propulsion and avionics bays are reusable, largely unchanged, and independent of the payload configuration. Such a design means that SSTL or a 3rd party manufacturer can manufacture the payload in parallel to the platform with integration taking place quite late in the schedule. In July 2003 SSTL signed a contract for ESA's first Galileo navigation satellite known as GSTBV2/A. The satellite is based on GMP and ESA plan to launch it into a MEO orbit late in 2005. The second flight of GMP is likely to be in 2006 carrying a geostationary payload

  13. Hurricane Satellite (HURSAT) Microwave (MW)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Hurricane Satellite (HURSAT) from Microwave (MW) observations of tropical cyclones worldwide data consist of raw satellite observations. The data derive from the...

  14. Satellite transmission of oceanographic data

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, E.S.; Desai, R.G.P.; DeSa, E.J.

    Oceanographic data collected on a research vessel has been transmitted to a shore laboratory using the INMARSAT maritime satellite The system configuration used, consisted of Satellite Communication Terminals interfaced to desk top computers...

  15. Satellite Ocean Heat Content Suite

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This collection contains an operational Satellite Ocean Heat Content Suite (SOHCS) product generated by NOAA National Environmental Satellite, Data, and Information...

  16. Monitoring Cyanobacteria with Satellites Webinar

    Science.gov (United States)

    real-world satellite applications can quantify cyanobacterial harmful algal blooms and related water quality parameters. Provisional satellite derived cyanobacteria data and different software tools are available to state environmental and health agencies.

  17. Defense Meteorological Satellite Program (DMSP)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Defense Meteorological Satellite Program (DMSP) satellites collect visible and infrared cloud imagery as well as monitoring the atmospheric, oceanographic,...

  18. Leonardo-BRDF: A New Generation Satellite Constellation

    Science.gov (United States)

    Esper, Jaime; Neeck, Steven; Wiscombe, Warren; Ryschkewitsch, Michael; Andary, J. (Technical Monitor)

    2000-01-01

    Instantaneous net radiation flux at the top of the atmosphere is one of the primary drivers of climate and global change. Since the dawn of the satellite era, great efforts and expense have gone into measuring this flux from single satellites and even (for a several-year period) from a constellation of three satellites called ERBE. However, the reflected solar flux is an angular and spectral integral over the so-called "BRDF" or Bidirectional Reflectance Distribution Function, which is the angular distribution of reflected solar radiation for each solar zenith angle and each wavelength. Previous radiation flux satellites could not measure instantaneous BRDF, so scientists have had to fall back on models or composites. Because their range of observed solar zenith angles was very limited due to sunsynchronous orbits, the resultant flux maps are too inaccurate to see the dynamics of radiation flux or to reliably correlate it with specific phenomena (hurricanes, biomass fires, urban pollution, dust outbreaks, etc.). Accuracy only becomes acceptable after monthly averaging, but this washes out almost all cause-and-effect information, further exacerbated by the lack of spectral resolution. Leonardo-BRDF is a satellite system designed to measure the instantaneous spectral BRDF using a formation of highly coordinated satellites, all pointing at the same Earth targets at the same time. It will allow scientists for the first time to assess the radiative forcing of climate due to specific phenomena, which is bound to be important in the ongoing debate about global warming and what is causing it. The formation is composed of two satellite types having, as instrument payloads, single highly-integrated miniature imaging spectrometers or radiometers. Two nearby "keystone" satellites anchor the formation and fly in static orbits. They employ wide field of view imaging spectrometers that are extremely light and compact. The keystone satellites are identical and can operate in

  19. Automated tracking for advanced satellite laser ranging systems

    Science.gov (United States)

    McGarry, Jan F.; Degnan, John J.; Titterton, Paul J., Sr.; Sweeney, Harold E.; Conklin, Brion P.; Dunn, Peter J.

    1996-06-01

    NASA's Satellite Laser Ranging Network was originally developed during the 1970's to track satellites carrying corner cube reflectors. Today eight NASA systems, achieving millimeter ranging precision, are part of a global network of more than 40 stations that track 17 international satellites. To meet the tracking demands of a steadily growing satellite constellation within existing resources, NASA is embarking on a major automation program. While manpower on the current systems will be reduced to a single operator, the fully automated SLR2000 system is being designed to operate for months without human intervention. Because SLR2000 must be eyesafe and operate in daylight, tracking is often performed in a low probability of detection and high noise environment. The goal is to automatically select the satellite, setup the tracking and ranging hardware, verify acquisition, and close the tracking loop to optimize data yield. TO accomplish the autotracking tasks, we are investigating (1) improved satellite force models, (2) more frequent updates of orbital ephemerides, (3) lunar laser ranging data processing techniques to distinguish satellite returns from noise, and (4) angular detection and search techniques to acquire the satellite. A Monte Carlo simulator has been developed to allow optimization of the autotracking algorithms by modeling the relevant system errors and then checking performance against system truth. A combination of simulator and preliminary field results will be presented.

  20. Telelibrary: Library Services via Satellite.

    Science.gov (United States)

    Liu, Rosa

    1979-01-01

    Investigates the provision of library services via satellite, explains briefly the operation and advantages of communication satellites, and discusses the various telecommunications equipment and services which, when coupled with satellite transmission, will enhance library activities. Demand trend projections for telecommunications services…

  1. An Ensemble Three-Dimensional Constrained Variational Analysis Method to Derive Large-Scale Forcing Data for Single-Column Models

    Science.gov (United States)

    Tang, Shuaiqi

    Atmospheric vertical velocities and advective tendencies are essential as large-scale forcing data to drive single-column models (SCM), cloud-resolving models (CRM) and large-eddy simulations (LES). They cannot be directly measured or easily calculated with great accuracy from field measurements. In the Atmospheric Radiation Measurement (ARM) program, a constrained variational algorithm (1DCVA) has been used to derive large-scale forcing data over a sounding network domain with the aid of flux measurements at the surface and top of the atmosphere (TOA). We extend the 1DCVA algorithm into three dimensions (3DCVA) along with other improvements to calculate gridded large-scale forcing data. We also introduce an ensemble framework using different background data, error covariance matrices and constraint variables to quantify the uncertainties of the large-scale forcing data. The results of sensitivity study show that the derived forcing data and SCM simulated clouds are more sensitive to the background data than to the error covariance matrices and constraint variables, while horizontal moisture advection has relatively large sensitivities to the precipitation, the dominate constraint variable. Using a mid-latitude cyclone case study in March 3rd, 2000 at the ARM Southern Great Plains (SGP) site, we investigate the spatial distribution of diabatic heating sources (Q1) and moisture sinks (Q2), and show that they are consistent with the satellite clouds and intuitive structure of the mid-latitude cyclone. We also evaluate the Q1 and Q2 in analysis/reanalysis, finding that the regional analysis/reanalysis all tend to underestimate the sub-grid scale upward transport of moist static energy in the lower troposphere. With the uncertainties from large-scale forcing data and observation specified, we compare SCM results and observations and find that models have large biases on cloud properties which could not be fully explained by the uncertainty from the large-scale forcing

  2. Infrared Astronomy Satellite

    Science.gov (United States)

    Ferrera, G. A.

    1981-09-01

    In 1982, the Infrared Astronomy Satellite (IRAS) will be launched into a 900-km sun-synchronous (twilight) orbit to perform an unbiased, all-sky survey of the far-infrared spectrum from 8 to 120 microns. Observations telemetered to ground stations will be compiled into an IR astronomy catalog. Attention is given the cryogenically cooled, 60-cm Ritchey-Chretien telescope carried by the satellite, whose primary and secondary mirrors are fabricated from beryllium by means of 'Cryo-Null Figuring'. This technique anticipates the mirror distortions that will result from cryogenic cooling of the telescope and introduces dimensional compensations for them during machining and polishing. Consideration is also given to the interferometric characterization of telescope performance and Cryo/Thermal/Vacuum simulated space environment testing.

  3. Satellite Control Laboratory

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Bak, Thomas

    2001-01-01

    The Satellite Laboratory at the Department of Control Engineering of Aalborg University (SatLab) is a dynamic motion facility designed for analysis and test of micro spacecraft. A unique feature of the laboratory is that it provides a completely gravity-free environment. A test spacecraft......-axis magnetometer, three piezoelectric gyros, and four reaction wheels in a tetrahedron configuration. The operation of the spacecraft is fully autonomous. The data flow between the transducers and the onboard computer placed physically outside the satellite is provided by a radio link. The purpose...... can be implemented in the laboratory, e.g. three-axis attitude control, slew manoeuvres, spins stabilization using magnetic actuation and/or reaction wheels. The spacecraft attitude can be determined applying magnetometer measurements....

  4. Thematic mapping from satellite imagery

    CERN Document Server

    Denègre, J

    2013-01-01

    Thematic Mapping from Satellite Imagery: A Guidebook discusses methods in producing maps using satellite images. The book is comprised of five chapters; each chapter covers one stage of the process. Chapter 1 tackles the satellite remote sensing imaging and its cartographic significance. Chapter 2 discusses the production processes for extracting information from satellite data. The next chapter covers the methods for combining satellite-derived information with that obtained from conventional sources. Chapter 4 deals with design and semiology for cartographic representation, and Chapter 5 pre

  5. Cooperative and cognitive satellite systems

    CERN Document Server

    Chatzinotas, Symeon; De Gaudenzi, Riccardo

    2015-01-01

    Cooperative and Cognitive Satellite Systems provides a solid overview of the current research in the field of cooperative and cognitive satellite systems, helping users understand how to incorporate state-of-the-art communication techniques in innovative satellite network architectures to enable the next generation of satellite systems. The book is edited and written by top researchers and practitioners in the field, providing a comprehensive explanation of current research that allows users to discover future technologies and their applications, integrate satellite and terrestrial systems

  6. Satellite Photometric Error Determination

    Science.gov (United States)

    2015-10-18

    Satellite Photometric Error Determination Tamara E. Payne, Philip J. Castro, Stephen A. Gregory Applied Optimization 714 East Monument Ave, Suite...advocate the adoption of new techniques based on in-frame photometric calibrations enabled by newly available all-sky star catalogs that contain highly...filter systems will likely be supplanted by the Sloan based filter systems. The Johnson photometric system is a set of filters in the optical

  7. Partial cross sections of helium satellites at medium photon energies

    Energy Technology Data Exchange (ETDEWEB)

    Wehlitz, R.; Sellin, I.A. [Univ. of Tennessee, Knoxville, TN (United States); Hemmers, O. [Univ. of Nevada, Las Vegas, NV (United States)] [and others

    1997-04-01

    Still of current interest is the important role of single ionization with excitation compared to single ionization alone. The coupling between the electrons and the incoming photon is a single-particle operator. Thus, an excitation in addition to an ionization, leading to a so-called satellite line in a photoelectron spectrum, is entirely due to electron-electron interaction and probes the electron correlation in the ground and final state. Therefore the authors have undertaken the study of the intensity of helium satellites He{sup +}nl (n = 2 - 6) relative to the main photoline (n = 1) as a function of photon energy at photon energies well above threshold up to 900 eV. From these results they could calculate the partial cross-sections of the helium satellites. In order to test the consistency of their satellite-to-1s ratios with published double-to-single photoionization ratios, the authors calculated the double-to-single photoionization ratio from their measured ratios using the theoretical energy-distribution curves of Chang and Poe and Le Rouzo and Dal Cappello which proved to be valid for photon energies below 120 eV. These calculated double-to-single ionization ratios agree fairly well with recent ion measurements. In the lower photon energy range the authors ratios agree better with the ratios of Doerner et al. while for higher photon energies the agreement is better with the values of Levin et al.

  8. Partial cross sections of helium satellites at medium photon energies

    International Nuclear Information System (INIS)

    Wehlitz, R.; Sellin, I.A.; Hemmers, O.

    1997-01-01

    Still of current interest is the important role of single ionization with excitation compared to single ionization alone. The coupling between the electrons and the incoming photon is a single-particle operator. Thus, an excitation in addition to an ionization, leading to a so-called satellite line in a photoelectron spectrum, is entirely due to electron-electron interaction and probes the electron correlation in the ground and final state. Therefore the authors have undertaken the study of the intensity of helium satellites He + nl (n = 2 - 6) relative to the main photoline (n = 1) as a function of photon energy at photon energies well above threshold up to 900 eV. From these results they could calculate the partial cross-sections of the helium satellites. In order to test the consistency of their satellite-to-1s ratios with published double-to-single photoionization ratios, the authors calculated the double-to-single photoionization ratio from their measured ratios using the theoretical energy-distribution curves of Chang and Poe and Le Rouzo and Dal Cappello which proved to be valid for photon energies below 120 eV. These calculated double-to-single ionization ratios agree fairly well with recent ion measurements. In the lower photon energy range the authors ratios agree better with the ratios of Doerner et al. while for higher photon energies the agreement is better with the values of Levin et al

  9. Mobile satellite service communications tests using a NASA satellite

    Science.gov (United States)

    Chambers, Katherine H.; Koschmeder, Louis A.; Hollansworth, James E.; ONeill, Jack; Jones, Robert E.; Gibbons, Richard C.

    1995-01-01

    Emerging applications of commercial mobile satellite communications include satellite delivery of compact disc (CD) quality radio to car drivers who can select their favorite programming as they drive any distance; transmission of current air traffic data to aircraft; and handheld communication of data and images from any remote corner of the world. Experiments with the enabling technologies and tests and demonstrations of these concepts are being conducted before the first satellite is launched by utilizing an existing NASA spacecraft.

  10. Radiometric Cross-Calibration of the Chilean Satellite FASat-C Using RapidEye and EO-1 Hyperion Data and a Simultaneous Nadir Overpass Approach

    Directory of Open Access Journals (Sweden)

    Carolina Barrientos

    2016-07-01

    Full Text Available The absolute radiometric calibration of a satellite sensor is the critical factor that ensures the usefulness of the acquired data for quantitative applications on remote sensing. This work presents the results of the first cross-calibration of the sensor on board the Sistema Satelital de Observación de la Tierra (SSOT Chilean satellite or Air Force Satellite FASat-C. RapidEye-MSI was chosen as the reference sensor, and a simultaneous Nadir Overpass Approach (SNO was applied. The biases caused by differences in the spectral responses of both instruments were compensated through an adjustment factor derived from EO-1 Hyperion data. Through this method, the variations affecting the radiometric response of New AstroSat Optical Modular Instrument (NAOMI-1, have been corrected based on collections over the Frenchman Flat calibration site. The results of a preliminary evaluation of the pre-flight and updated coefficients have shown a significant improvement in the accuracy of at-sensor radiances and TOA reflectances: an average agreement of 2.63% (RMSE was achieved for the multispectral bands of both instruments. This research will provide a basis for the continuity of calibration and validation tasks of future Chilean space missions.

  11. Satellite observed impacts of wildfires on regional atmosphere composition and shortwave radiative forcing: multiple cases study

    Science.gov (United States)

    Fu, Y.; Li, R.; Huang, J.; Bergeron, Y.; Fu, Y.

    2017-12-01

    Emissions of aerosols and trace gases from wildfires and the direct shortwave radiative forcing were studied using multi-satellite/sensor observations from Aqua Moderate-Resolution Imaging Spectroradiometer (MODIS), Aqua Atmospheric Infrared Sounder (AIRS), Aura Ozone Monitoring Instrument (OMI), and Aqua Cloud's and the Earth's Radiant Energy System (CERES). The selected cases occurred in Northeast of China (NEC), Siberia of Russia, California of America have dominant fuel types of cropland, mixed forest and needleleaf forest, respectively. The Fire radiative power (FRP) based emission coefficients (Ce) of aerosol, NOx (NO2+NO), formaldehyde (HCHO), and carbon monoxide (CO) showed significant differences from case to case. 1) the FRP of the cropland case in NEC is strongest, however, the Ce of aerosol is the lowest (20.51 ± 2.55 g MJ-1). The highest Ce of aerosol is 71.34 ± 13.24 g MJ-1 in the needleleaf fire case in California. 2) For NOx, the highest Ce existed in the cropland case in NEC (2.76 ± 0.25 g MJ-1), which is more than three times of those in the forest fires in Siberia and California. 3) The Ce of CO is 70.21±10.97 and 88.38±46.16 g MJ-1 in the forest fires in Western Siberia and California, which are about four times of that in cropland fire. 4) The variation of Ce of HCHO are relatively small among cases. Strong spatial correlations are found among aerosol optical depth (AOD), NOx, HCHO, and CO. The ratios of NOx to AOD, HCHO, and CO in the cropland case in NEC show much higher values than those in other cases. Although huge differences of emissions and composition ratios exist among cases, the direct shortwave (SW) radiative forcing efficiency (SWARFE) of smoke at the top of the atmosphere (TOA) are in good agreement, with the shortwave radiative forcing efficiencies values of 20.09 to 22.93 per unit AOD. Results in this study reveal noteworthy variations of the FRP-based emissions coefficient and relative chemical composition in the smoke

  12. Satellite Remote Sensing of Snow/Ice Albedo over the Himalayas

    Science.gov (United States)

    Hsu, N. Christina; Gautam, Ritesh

    2012-01-01

    The Himalayan glaciers and snowpacks play an important role in the hydrological cycle over Asia. The seasonal snow melt from the Himalayan glaciers and snowpacks is one of the key elements to the livelihood of the downstream densely populated regions of South Asia. During the pre-monsoon season (April-May-June), South Asia not only experiences the reversal of the regional meridional tropospheric temperature gradient (i.e., the onset of the summer monsoon), but also is being bombarded by dry westerly airmass that transports mineral dust from various Southwest Asian desert and arid regions into the Indo-Gangetic Plains in northern India. Mixed with heavy anthropogenic pollution, mineral dust constitutes the bulk of regional aerosol loading and forms an extensive and vertically extended brown haze lapping against the southern slopes of the Himalayas. Episodic dust plumes are advected over the Himalayas, and are discernible in satellite imagery, resulting in dust-capped snow surface. Motivated by the potential implications of accelerated snowmelt, we examine the changes in radiative energetics induced by aerosol transport over the Himalayan snow cover by utilizing space borne observations. Our objective lies in the investigation of potential impacts of aerosol solar absorption on the Top-of-Atmosphere (TOA) spectral reflectivity and the broadband albedo, and hence the accelerated snowmelt, particularly in the western Himalayas. Lambertian Equivalent Reflectivity (LER) in the visible and near-infrared wavelengths, derived from Moderate Resolution Imaging Spectroradiometer radiances, is used to generate statistics for determining perturbation caused due to dust layer over snow surface in over ten years of continuous observations. Case studies indicate significant reduction of LER ranging from 5 to 8% in the 412-860nm spectra. Broadband flux observations, from the Clouds and the Earth's Radiant Energy System, are also used to investigate changes in shortwave TOA flux over

  13. Satellite disintegration dynamics

    Science.gov (United States)

    Dasenbrock, R. R.; Kaufman, B.; Heard, W. B.

    1975-01-01

    The subject of satellite disintegration is examined in detail. Elements of the orbits of individual fragments, determined by DOD space surveillance systems, are used to accurately predict the time and place of fragmentation. Dual time independent and time dependent analyses are performed for simulated and real breakups. Methods of statistical mechanics are used to study the evolution of the fragment clouds. The fragments are treated as an ensemble of non-interacting particles. A solution of Liouville's equation is obtained which enables the spatial density to be calculated as a function of position, time and initial velocity distribution.

  14. Do asteroids have satellites

    International Nuclear Information System (INIS)

    Weidenschilling, S.J.; Paolicchi, P.; Zappala, V.

    1989-01-01

    A substantial body of indirect evidence suggests that some asteroids have satelities, although none has been detected unambiguously. Collisions between asteroids provide physically plausible mechanisms for the production of binaries, but these operate with low probability; only a small minority of asteroids are likely to have satellites. The abundance of binary asteroids can constrain the collisional history of the entire belt population. The allowed angular momentum of binaries and their rate of tidal evolution limit separations to no more than a few tens of the primary's radii. Their expected properties are consistent with failure to detect them by current imaging techniques

  15. China Satellite Navigation Conference

    CERN Document Server

    Liu, Jingnan; Fan, Shiwei; Wang, Feixue

    2016-01-01

    These Proceedings present selected research papers from CSNC2016, held during 18th-20th May in Changsha, China. The theme of CSNC2016 is Smart Sensing, Smart Perception. These papers discuss the technologies and applications of the Global Navigation Satellite System (GNSS), and the latest progress made in the China BeiDou System (BDS) especially. They are divided into 12 topics to match the corresponding sessions in CSNC2016, which broadly covered key topics in GNSS. Readers can learn about the BDS and keep abreast of the latest advances in GNSS techniques and applications.

  16. China Satellite Navigation Conference

    CERN Document Server

    Liu, Jingnan; Yang, Yuanxi; Fan, Shiwei; Yu, Wenxian

    2017-01-01

    These proceedings present selected research papers from CSNC2017, held during 23th-25th May in Shanghai, China. The theme of CSNC2017 is Positioning, Connecting All. These papers discuss the technologies and applications of the Global Navigation Satellite System (GNSS), and the latest progress made in the China BeiDou System (BDS) especially. They are divided into 12 topics to match the corresponding sessions in CSNC2017, which broadly covered key topics in GNSS. Readers can learn about the BDS and keep abreast of the latest advances in GNSS techniques and applications.

  17. Understanding satellite navigation

    CERN Document Server

    Acharya, Rajat

    2014-01-01

    This book explains the basic principles of satellite navigation technology with the bare minimum of mathematics and without complex equations. It helps you to conceptualize the underlying theory from first principles, building up your knowledge gradually using practical demonstrations and worked examples. A full range of MATLAB simulations is used to visualize concepts and solve problems, allowing you to see what happens to signals and systems with different configurations. Implementation and applications are discussed, along with some special topics such as Kalman Filter and Ionosphere. W

  18. Using In Situ Observations and Satellite Retrievals to Constrain Large-Eddy Simulations and Single-Column Simulations: Implications for Boundary-Layer Cloud Parameterization in the NASA GISS GCM

    Science.gov (United States)

    Remillard, J.

    2015-12-01

    Two low-cloud periods from the CAP-MBL deployment of the ARM Mobile Facility at the Azores are selected through a cluster analysis of ISCCP cloud property matrices, so as to represent two low-cloud weather states that the GISS GCM severely underpredicts not only in that region but also globally. The two cases represent (1) shallow cumulus clouds occurring in a cold-air outbreak behind a cold front, and (2) stratocumulus clouds occurring when the region was dominated by a high-pressure system. Observations and MERRA reanalysis are used to derive specifications used for large-eddy simulations (LES) and single-column model (SCM) simulations. The LES captures the major differences in horizontal structure between the two low-cloud fields, but there are unconstrained uncertainties in cloud microphysics and challenges in reproducing W-band Doppler radar moments. The SCM run on the vertical grid used for CMIP-5 runs of the GCM does a poor job of representing the shallow cumulus case and is unable to maintain an overcast deck in the stratocumulus case, providing some clues regarding problems with low-cloud representation in the GCM. SCM sensitivity tests with a finer vertical grid in the boundary layer show substantial improvement in the representation of cloud amount for both cases. GCM simulations with CMIP-5 versus finer vertical gridding in the boundary layer are compared with observations. The adoption of a two-moment cloud microphysics scheme in the GCM is also tested in this framework. The methodology followed in this study, with the process-based examination of different time and space scales in both models and observations, represents a prototype for GCM cloud parameterization improvements.

  19. Living antennas on communication satellites

    DEFF Research Database (Denmark)

    Lumholt, Michael

    2003-01-01

    Crises change the global pattern of communication. The communications problems occur because the satellites are optimized to cover specific geographic areas, and these areas cannot be altered once the satellites are in Earth orbit. An effective solution to the problem is to equip communication sa...... satellites with "living" antennas that can adjust their radiation coverage areas according to the new demands. The development of living antennas is, therefore, among the focus areas identified and supported by the European Space Agency, ESA....

  20. Agent control of cooperating satellites

    OpenAIRE

    Lincoln, N.K.; Veres, S.M.; Dennis, Louise; Fisher, Michael; Lisitsa, Alexei

    2011-01-01

    A novel, hybrid, agent architecture for (small)swarms of satellites has been developed. The software architecture for each satellite comprises ahigh-level rational agent linked to a low-level control system. The rational agent forms dynamicgoals, decides how to tackle them and passes theactual implementation of these plans to the control layer. The rational agent also has access to aMatLabmodel of the satellite dynamics, thus allowing it to carry out selective hypothetical reasoningabout pote...

  1. Trends in mobile satellite communication

    Science.gov (United States)

    Johannsen, Klaus G.; Bowles, Mike W.; Milliken, Samuel; Cherrette, Alan R.; Busche, Gregory C.

    1993-01-01

    Ever since the U.S. Federal Communication Commission opened the discussion on spectrum usage for personal handheld communication, the community of satellite manufacturers has been searching for an economically viable and technically feasible satellite mobile communication system. Hughes Aircraft Company and others have joined in providing proposals for such systems, ranging from low to medium to geosynchronous orbits. These proposals make it clear that the trend in mobile satellite communication is toward more sophisticated satellites with a large number of spot beams and onboard processing, providing worldwide interconnectivity. Recent Hughes studies indicate that from a cost standpoint the geosynchronous satellite (GEOS) is most economical, followed by the medium earth orbit satellite (MEOS) and then by the low earth orbit satellite (LEOS). From a system performance standpoint, this evaluation may be in reverse order, depending on how the public will react to speech delay and collision. This paper discusses the trends and various mobile satellite constellations in satellite communication under investigation. It considers the effect of orbital altitude and modulation/multiple access on the link and spacecraft design.

  2. Magnetic Satellite Missions and Data

    DEFF Research Database (Denmark)

    Olsen, Nils; Kotsiaros, Stavros

    2011-01-01

    Although the first satellite observations of the Earth’s magnetic field were already taken more than 50 years ago, continuous geomagnetic measurements from space are only available since 1999. The unprecedented time-space coverage of this recent data set opened revolutionary new possibilities...... for exploring the Earth’s magnetic field from space. In this chapter we discuss characteristics of satellites measuring the geomagnetic field and report on past, present and upcoming magnetic satellite missions. We conclude with some basics about space magnetic gradiometry as a possible path for future...... exploration of Earth’s magnetic field with satellites....

  3. Effective fiber hypertrophy in satellite cell-depleted skeletal muscle

    Science.gov (United States)

    McCarthy, John J.; Mula, Jyothi; Miyazaki, Mitsunori; Erfani, Rod; Garrison, Kelcye; Farooqui, Amreen B.; Srikuea, Ratchakrit; Lawson, Benjamin A.; Grimes, Barry; Keller, Charles; Van Zant, Gary; Campbell, Kenneth S.; Esser, Karyn A.; Dupont-Versteegden, Esther E.; Peterson, Charlotte A.

    2011-01-01

    An important unresolved question in skeletal muscle plasticity is whether satellite cells are necessary for muscle fiber hypertrophy. To address this issue, a novel mouse strain (Pax7-DTA) was created which enabled the conditional ablation of >90% of satellite cells in mature skeletal muscle following tamoxifen administration. To test the hypothesis that satellite cells are necessary for skeletal muscle hypertrophy, the plantaris muscle of adult Pax7-DTA mice was subjected to mechanical overload by surgical removal of the synergist muscle. Following two weeks of overload, satellite cell-depleted muscle showed the same increases in muscle mass (approximately twofold) and fiber cross-sectional area with hypertrophy as observed in the vehicle-treated group. The typical increase in myonuclei with hypertrophy was absent in satellite cell-depleted fibers, resulting in expansion of the myonuclear domain. Consistent with lack of nuclear addition to enlarged fibers, long-term BrdU labeling showed a significant reduction in the number of BrdU-positive myonuclei in satellite cell-depleted muscle compared with vehicle-treated muscle. Single fiber functional analyses showed no difference in specific force, Ca2+ sensitivity, rate of cross-bridge cycling and cooperativity between hypertrophied fibers from vehicle and tamoxifen-treated groups. Although a small component of the hypertrophic response, both fiber hyperplasia and regeneration were significantly blunted following satellite cell depletion, indicating a distinct requirement for satellite cells during these processes. These results provide convincing evidence that skeletal muscle fibers are capable of mounting a robust hypertrophic response to mechanical overload that is not dependent on satellite cells. PMID:21828094

  4. Gigabit Satellite Network for NASA's Advanced Communication Technology Satellite (ACTS)

    Science.gov (United States)

    Hoder, Douglas; Bergamo, Marcos

    1996-01-01

    The advanced communication technology satellite (ACTS) gigabit satellite network provides long-haul point-to-point and point-to-multipoint full-duplex SONET services over NASA's ACTS. at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with terrestrial fiber networks. Data multiplexing over the satellite is accomplished using time-division multiple access (TDMA) techniques coordinated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon encoding. providing virtually error-free transmission under most weather conditions. Unique to the system are a TDMA frame structure and satellite synchronization mechanism that allow: (a) very efficient utilization of the satellite capacity: (b) over-the-satellite dosed-loop synchronization of the network in configurations with up to 64 ground stations: and (c) ground station initial acquisition without collisions with existing signalling or data traffic. The user interfaces are compatible with SONET standards, performing the function of conventional SONET multiplexers and. as such. can be: readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP). and includes an over-the-satellite signalling network and backup terrestrial internet (IP-based) connectivity. A description of the ground stations is also included.

  5. International Satellite Law

    Science.gov (United States)

    von der Dunk, Frans

    2017-07-01

    there are the major categories of space applications—as these have started to impact everyday life on earth: the involvement of satellites in communications infrastructures and services, the most commercialized area of space applications yet; the special issue of space serving to mitigate disasters and their consequences on earth; the use of satellites for remote sensing purposes ranging from weather and climate monitoring to spying; and the use of satellites for positioning, navigation, and timing.

  6. The Future of Satellite Communications Technology.

    Science.gov (United States)

    Nowland, Wayne

    1985-01-01

    Discusses technical advances in satellite technology since the 1960s, and the International Telecommunications Satellite Organization's role in these developments; describes how AUSSAT, Australia's domestic satellite system, exemplifies the latest developments in satellite technology; and reviews satellite system features, possible future…

  7. Ambiguity resolution for satellite Doppler positioning systems

    Science.gov (United States)

    Argentiero, P.; Marini, J.

    1979-01-01

    The implementation of satellite-based Doppler positioning systems frequently requires the recovery of transmitter position from a single pass of Doppler data. The least-squares approach to the problem yields conjugate solutions on either side of the satellite subtrack. It is important to develop a procedure for choosing the proper solution which is correct in a high percentage of cases. A test for ambiguity resolution which is the most powerful in the sense that it maximizes the probability of a correct decision is derived. When systematic error sources are properly included in the least-squares reduction process to yield an optimal solution the test reduces to choosing the solution which provides the smaller valuation of the least-squares loss function. When systematic error sources are ignored in the least-squares reduction, the most powerful test is a quadratic form comparison with the weighting matrix of the quadratic form obtained by computing the pseudoinverse of a reduced-rank square matrix. A formula for computing the power of the most powerful test is provided. Numerical examples are included in which the power of the test is computed for situations that are relevant to the design of a satellite-aided search and rescue system.

  8. Consensus of satellite cluster flight using an energy-matching optimal control method

    Science.gov (United States)

    Luo, Jianjun; Zhou, Liang; Zhang, Bo

    2017-11-01

    This paper presents an optimal control method for consensus of satellite cluster flight under a kind of energy matching condition. Firstly, the relation between energy matching and satellite periodically bounded relative motion is analyzed, and the satellite energy matching principle is applied to configure the initial conditions. Then, period-delayed errors are adopted as state variables to establish the period-delayed errors dynamics models of a single satellite and the cluster. Next a novel satellite cluster feedback control protocol with coupling gain is designed, so that the satellite cluster periodically bounded relative motion consensus problem (period-delayed errors state consensus problem) is transformed to the stability of a set of matrices with the same low dimension. Based on the consensus region theory in the research of multi-agent system consensus issues, the coupling gain can be obtained to satisfy the requirement of consensus region and decouple the satellite cluster information topology and the feedback control gain matrix, which can be determined by Linear quadratic regulator (LQR) optimal method. This method can realize the consensus of satellite cluster period-delayed errors, leading to the consistency of semi-major axes (SMA) and the energy-matching of satellite cluster. Then satellites can emerge the global coordinative cluster behavior. Finally the feasibility and effectiveness of the present energy-matching optimal consensus for satellite cluster flight is verified through numerical simulations.

  9. Satellite Control Laboratory

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Bak, Thomas

    2001-01-01

    The Satellite Laboratory at the Department of Control Engineering of Aalborg University (SatLab) is a dynamic motion facility designed for analysis and test of micro spacecraft. A unique feature of the laboratory is that it provides a completely gravity-free environment. A test spacecraft...... of the laboratory is to conduct dynamic tests of the control and attitude determination algorithms during nominal operation and in abnormal conditions. Further it is intended to use SatLab for validation of various algorithms for fault detection, accommodation and supervisory control. Different mission objectives...... can be implemented in the laboratory, e.g. three-axis attitude control, slew manoeuvres, spins stabilization using magnetic actuation and/or reaction wheels. The spacecraft attitude can be determined applying magnetometer measurements...

  10. The solar power satellite

    Energy Technology Data Exchange (ETDEWEB)

    Combes, P.F.

    1982-01-01

    The construction, launch, components, and operations of satellite solar power systems (SSPS) for direct beaming of solar energy converted to electricity to earth stations are outlined. The reference designs of either Si or concentrator GaAs solar cell assemblies large enough to project 5 GW of power are described. The beam will be furnished by klystrons or amplitrons for reception by rectennas on earth. Conforming to the law of amplitude and the equiphase law will permit high efficiencies, pointing accuracy, and low power deposition/sq cm, thus avoiding environmental problems, although some telecommunications systems may suffer interference. The construction of the dipole rectenna grid is sketched, noting that one receiver would be an ellipse sized at 10 x 13 km. Various forms of pollution which could result from the construction of an SSPS are examined.

  11. Congestion control and routing over satellite networks

    Science.gov (United States)

    Cao, Jinhua

    ) method and then develop a novel on-demand routing system named Cross Entropy Accelerated Ant Routing System (CEAARS) for regular constellation LEO satellite networks. By implementing simulations on an Iridium-like satellite network, we compare the proposed CEAARS algorithm with the two approaches to adaptive routing protocols on the Internet: distance-vector (DV) and link-state (LS), as well as with the original Cross Entropy Ant Routing System (CEARS). DV algorithms are based on distributed Bellman Ford algorithm, and LS algorithms are implementation of Dijkstras single source shortest path. The results show that CEAARS not only remarkably improves the convergence speed of achieving optimal or suboptimal paths, but also reduces the number of overhead ants (management packets).

  12. Launching the First Indian Satellite

    Indian Academy of Sciences (India)

    materials and chemicals, rocket propulsion, satellite technology, control and guidance system, etc. ... entire country, especially the rural areas, and in the survey and management of natural resources. Listeners are no .... satellite will store the information over a longer period and then on command from the ground station at ...

  13. Integrated Satellite-HAP Systems

    DEFF Research Database (Denmark)

    Cianca, Ernestina; De Sanctis, Mauro; De Luise, Aldo

    2005-01-01

    Thus far, high-altitude platform (HAP)-based systems have been mainly conceived as an alternative to satellites for complementing the terrestrial network. This article aims to show that HAP should no longer be seen as a competitor technology by investors of satellites, but as a key element for an...

  14. Newspaper Uses of Satellite Technology.

    Science.gov (United States)

    Johns, David

    Replacing slower mail service, satellite transmission now gives the newspaper industry a practical and almost spontaneous method for sending all kinds of information to any newspaper across the country. Unlike other communication industries, newspapers did not begin to make widespread use of satellite technology until 1979, when government…

  15. Satellite Demonstration: The Videodisc Technology.

    Science.gov (United States)

    Propp, George; And Others

    1979-01-01

    Originally part of a symposium on educational media for the deaf, the paper describes a satellite demonstration of video disc materials. It is explained that a panel of deaf individuals in Washington, D.C. and another in Nebraska came into direct two-way communication for the first time, and video disc materials were broadcast via the satellite.…

  16. A Primer on Satellite Equipment.

    Science.gov (United States)

    Doan, Michael

    1992-01-01

    Information provided for school districts desiring to offer distance education courses to their students describes the kind of satellite dish needed; its size, sturdiness, placement, and number of dishes needed; satellite receivers; the function of a descrambler; copyright restrictions; features of an Integrated Receiver/Descrambler; selecting a…

  17. Accumulation of satellites

    International Nuclear Information System (INIS)

    Safronov, V.S.; Ruskol, E.L.

    1977-01-01

    Formation and evolution of circumplanetary satellite swarms are investigated. Characteristic times of various processes are estimated. The characteristic time for the accumulation of the bodies in the swarm was several orders of magnitude shorter than that of the planet, i.e. than the time of the replenishment of the material by the swarm (10 8 yr). The model of the accumulation of the swarm is constructed taking into account the increase of its mass due to trapping of heliocentrically moving particles and its decrease due to outfall of the inner part of the swarm onto the growing planet. The accumulation of circumplanetary bodies is also considered. The main features of the evolution of the swarm essentially depend on the size distribution of bodies in the swarm and in the zone of the planet and also on the degree of the concentration of the swarm mass toward the planet. If the sum of the exponents of the inverse power laws of these distributions is less than 7, the model of the transparent swarm developed in this paper should be preferred. When this sum is greater than 7, the model of opaque swarm suggested by A. Harris and W.M. Kaula is better. There is predominant trapping of small particles into the swarm due to their more frequent collisions. Optical thickness of the protoplanetary cloud in radial direction is estimated. It is shown that at the final stage of the planetary accumulation, the cloud was semitransparent in the region of terrestrial planets and volatile substances evaporated at collisions could be swept out from the outer parts of the satellite swarm by the solar wind

  18. Introducing you to satellite operated data collection platforms (DCP).

    CSIR Research Space (South Africa)

    Stavropoulos, CC

    1977-09-01

    Full Text Available and operate in the VHF, UHF or microwave bands. By using a satellite as a repeater, large distances over land and sea can be covered with a single repeater in the sky. Trans-continental links for communication purposes have been operational for many years...

  19. Sky alert! when satellites fail

    CERN Document Server

    Johnson, Les

    2013-01-01

    How much do we depend on space satellites? Defense, travel, agriculture, weather forecasting, mobile phones and broadband, commerce...the list seems endless. But what would our live be like if the unimaginable happened and, by accident or design, those space assets disappeared? Sky Alert! explores what our world would be like, looking in turn at areas where the loss could have catastrophic effects. The book - demonstrates our dependence on space technology and satellites; - outlines the effect on our economy, defense, and daily lives if satellites and orbiting spacecraft were destroyed; - illustrates the danger of dead satellites, spent rocket stages, and space debris colliding with a functioning satellites; - demonstrates the threat of dramatically increased radiation levels associated with geomagnetic storms; - introduces space as a potential area of conflict between nations.

  20. Encryption protection for communication satellites

    Science.gov (United States)

    Sood, D. R.; Hoernig, O. W., Jr.

    In connection with the growing importance of the commercial communication satellite systems and the introduction of new technological developments, users and operators of these systems become increasingly concerned with aspects of security. The user community is concerned with maintaining confidentiality and integrity of the information being transmitted over the satellite links, while the satellite operators are concerned about the safety of their assets in space. In response to these concerns, the commercial satellite operators are now taking steps to protect the communication information and the satellites. Thus, communication information is being protected by end-to-end encryption of the customer communication traffic. Attention is given to the selection of the NBS DES algorithm, the command protection systems, and the communication protection systems.

  1. Polar-Orbiting Satellite (POES) Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Visible and Infrared satellite imagery taken from camera systems or radiometer instruments on satellites in orbit around the poles. Satellite campaigns include...

  2. Investigations in Satellite MIMO Channel Modeling: Accent on Polarization

    Directory of Open Access Journals (Sweden)

    Karagiannidis George K

    2007-01-01

    Full Text Available Due to the much different environment in satellite and terrestrial links, possibilities in and design of MIMO systems are rather different as well. After pointing out these differences and problems arising from them, two MIMO designs are shown rather well adapted to satellite link characteristics. Cooperative diversity seems to be applicable; its concept is briefly presented without a detailed discussion, leaving solving particular satellite problems to later work. On the other hand, a detailed discussion of polarization time-coded diversity (PTC is given. A physical-statistical model for dual-polarized satellite links is presented together with measuring results validating the model. The concept of 3D polarization is presented as well as briefly describing compact 3D-polarized antennas known from the literature and applicable in satellite links. A synthetic satellite-to-indoor link is constructed and its electromagnetic behavior is simulated via the FDTD (finite-difference time-domain method. Previous result of the authors states that in 3D-PTC situations, MIMO capacity can be about two times higher than SIMO (single-input multiple-output capacity while a diversity gain of nearly is further verified via extensive FDTD computer simulation.

  3. Optical neural network system for pose determination of spinning satellites

    Science.gov (United States)

    Lee, Andrew; Casasent, David

    1990-01-01

    An optical neural network architecture and algorithm based on a Hopfield optimization network are presented for multitarget tracking. This tracker utilizes a neuron for every possible target track, and a quadratic energy function of neural activities which is minimized using gradient descent neural evolution. The neural net tracker is demonstrated as part of a system for determining position and orientation (pose) of spinning satellites with respect to a robotic spacecraft. The input to the system is time sequence video from a single camera. Novelty detection and filtering are utilized to locate and segment novel regions from the input images. The neural net multitarget tracker determines the correspondences (or tracks) of the novel regions as a function of time, and hence the paths of object (satellite) parts. The path traced out by a given part or region is approximately elliptical in image space, and the position, shape and orientation of the ellipse are functions of the satellite geometry and its pose. Having a geometric model of the satellite, and the elliptical path of a part in image space, the three-dimensional pose of the satellite is determined. Digital simulation results using this algorithm are presented for various satellite poses and lighting conditions.

  4. Theory of satellite geodesy applications of satellites to geodesy

    CERN Document Server

    Kaula, William M

    2000-01-01

    The main purpose of this classic text is to demonstrate how Newtonian gravitational theory and Euclidean geometry can be used and developed in the earth's environment. The second is to collect and explain some of the mathematical techniques developed for measuring the earth by satellite.Book chapters include discussions of the earth's gravitational field, with special emphasis on spherical harmonies and the potential of the ellipsoid; matrices and orbital geometry; elliptic motion, linear perturbations, resonance, and other aspects of satellite orbit dynamics; the geometry of satellite obser

  5. Similarity of satellite DNA properties in the order Rodentia

    Energy Technology Data Exchange (ETDEWEB)

    Mazrimas, J A; Hatch, F T

    1977-09-01

    We have characterized satellite DNAs from 9 species of kangaroo rat (Dipodomys) and have shown that the HS-..cap alpha.. and HS-..beta.. satellites, where present, are nearly identical in all species as to melting transition midpoint (Tm), and density in neutral CsCl, alkaline CsCl, and Cs/sub 2/SO/sub 4/-Ag/sup +/ gradients. However, the MS satellites exist in two internally similar classes. The satellite DNAs from three other rodents were characterized (densities listed are in neutral CsCl). The pocket gopher, Thomomys bottae, contains Th-..cap alpha.. (1.713 g/ml) and Th-..beta.. (1.703 g/ml). The guinea pig (Cavia porcellus) contains Ca-..cap alpha.., Ca-..beta.., and Ca-..gamma.. at densities of 1.706 g/ml, 1.704 g/ml, and 1.704 g/ml, respectively. The antelope ground squirrel (Ammospermophilus harrisi) contains Am-..cap alpha.., 1.708 g/ml, Am-..beta.., 1.717 g/ml, and Am-..gamma.., 1.707 g/ml. The physical and chemical properties of the alpha-satellites from the above four rodents representing four different families in two suborders of Rodentia were compared. They show nearly identical Tm, nucleoside composition of single strands, and single strand densities in alkaline CsCl. Similar comparisons on the second or third satellite DNAs from these rodents also indicate a close relationship to each other. Thus the high degree of similarity of satellite sequences found in such a diverse group of rodents suggests a cellular function that is subject to natural selection, and implies that these sequences have been conserved over a considerable span of evolutionary time since the divergence of these rodents about 50 million years ago.

  6. Similarity of satellite DNA properties in the order Rodentia

    Energy Technology Data Exchange (ETDEWEB)

    Mazrimas, J A; Hatch, F T

    1977-09-01

    Satellite DNAs from 9 species of kangaroo rat (Dipodomys) have been characterized and have shown that the HS-..cap alpha.. and HS-..beta.. satellites, where present, are nearly identical in all species as to melting transition midpoint (Tm), and density in neutral CsCl, alkaline CsCl, and Cs/sub 2/SO/sub 4/-Ag/sup +/ gradients. However, the MS satellites exist in two internally similar classes. The satellite DNAs from three other rodents were characterized (densities listed are in neutral CsCl). The pocket gopher, Thomomys bottae, contains Th-..cap alpha.. (1.713 g/ml) and Th..beta.. (1.703 g/ml). The guinea pig (Cavia porcellus) contains Ca-..cap alpha.., Ca-..beta.. and Ca-..gamma.. at densities of 1.706 g/ml, 1.704 g/ml and 1.704 g/ml, respectively. The antelope ground squirrel (Ammospermophilus harrisi) contains Am-..cap alpha.., 1.708 g/ml, Am-..beta.., 1.717 g/ml, and Am-..gamma.., 1.707 g/ml. The physical and chemical properties of the alpha-satellites from the above four rodents representing four different families in two suborders of Rodentia were compared. They show nearly identical Tm, nucleoside composition of single strands, and single strand densities in alkaline CsCl. Similar comparisons on the second or third satellite DNAs from these rodents also indicate a close relationship to each other. Thus the high degree of similarity of satellite sequences found in such a diverse group of rodents suggests a cellular function that is subject to natural selection, and implies that these sequences have been conserved over a considerable span of evolutionary time since the divergence of these rodents about 50 million years ago.

  7. Ground-to-satellite quantum teleportation.

    Science.gov (United States)

    Ren, Ji-Gang; Xu, Ping; Yong, Hai-Lin; Zhang, Liang; Liao, Sheng-Kai; Yin, Juan; Liu, Wei-Yue; Cai, Wen-Qi; Yang, Meng; Li, Li; Yang, Kui-Xing; Han, Xuan; Yao, Yong-Qiang; Li, Ji; Wu, Hai-Yan; Wan, Song; Liu, Lei; Liu, Ding-Quan; Kuang, Yao-Wu; He, Zhi-Ping; Shang, Peng; Guo, Cheng; Zheng, Ru-Hua; Tian, Kai; Zhu, Zhen-Cai; Liu, Nai-Le; Lu, Chao-Yang; Shu, Rong; Chen, Yu-Ao; Peng, Cheng-Zhi; Wang, Jian-Yu; Pan, Jian-Wei

    2017-09-07

    An arbitrary unknown quantum state cannot be measured precisely or replicated perfectly. However, quantum teleportation enables unknown quantum states to be transferred reliably from one object to another over long distances, without physical travelling of the object itself. Long-distance teleportation is a fundamental element of protocols such as large-scale quantum networks and distributed quantum computation. But the distances over which transmission was achieved in previous teleportation experiments, which used optical fibres and terrestrial free-space channels, were limited to about 100 kilometres, owing to the photon loss of these channels. To realize a global-scale 'quantum internet' the range of quantum teleportation needs to be greatly extended. A promising way of doing so involves using satellite platforms and space-based links, which can connect two remote points on Earth with greatly reduced channel loss because most of the propagation path of the photons is in empty space. Here we report quantum teleportation of independent single-photon qubits from a ground observatory to a low-Earth-orbit satellite, through an uplink channel, over distances of up to 1,400 kilometres. To optimize the efficiency of the link and to counter the atmospheric turbulence in the uplink, we use a compact ultra-bright source of entangled photons, a narrow beam divergence and high-bandwidth and high-accuracy acquiring, pointing and tracking. We demonstrate successful quantum teleportation of six input states in mutually unbiased bases with an average fidelity of 0.80 ± 0.01, well above the optimal state-estimation fidelity on a single copy of a qubit (the classical limit). Our demonstration of a ground-to-satellite uplink for reliable and ultra-long-distance quantum teleportation is an essential step towards a global-scale quantum internet.

  8. VLBI Observations of Geostationary Satellites

    Science.gov (United States)

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

    2013-08-01

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

  9. Satellite combined heat and power plants and their legal autonomy

    International Nuclear Information System (INIS)

    Loibl, Helmut

    2014-01-01

    Since the landmark decision by the German Court of Justice concerning the term ''plant'' in the context of biogas plants it should be clear beyond doubt that satellite combined heat and power plants (CHPs) are legally autonomous plants pursuant to Para. 3 No. 1 of the Renewable Energy Law (EEG). What has yet to be finally resolved are the conditions under which satellite CHPs are to be regarded as autonomous. This will be a question of distance on the one hand and of operation autonomy on the other. In the individual case both these factors will have to be assessed from the perspective of an average objective, informed citizen. To the extent that its heat and electricity are being utilised in a meaningful manner, the plant's autonomy will be beyond doubt, at least in operational terms. Regarding the remuneration to be paid for satellite CHPs the only case requiring special consideration is when a CHP falls under the EEG of 2012. In this case Para. 1 Section 1 Sentence 2 EEG provides that the remuneration for the CHP in question is to be calculated as if there was a single overall plant. To the extent that none of the CHPs fall under the EEG of 2012, the ruling remains that there is a separate entitlement to remuneration for each satellite CHP. This also holds in cases where satellite CHPs that were commissioned after 1 January 2012 are relocated. When a satellite CHP is replaced by a new one, the rate and duration of remuneration remain unchanged. However, when a new satellite CHP is added to an existing satellite CHP via a gas collector line it is to be treated according to the decisions of the Federal Court of Justice concerning biogas plant extensions: It falls under the law that applies to the existing CHP and has an entitlement to a new minimum remuneration period, albeit subject to the degression rate provided by the EEG version in question.

  10. Security Concepts for Satellite Links

    Science.gov (United States)

    Tobehn, C.; Penné, B.; Rathje, R.; Weigl, A.; Gorecki, Ch.; Michalik, H.

    2008-08-01

    The high costs to develop, launch and maintain a satellite network makes protecting the assets imperative. Attacks may be passive such as eavesdropping on the payload data. More serious threat are active attacks that try to gain control of the satellite, which may lead to the total lost of the satellite asset. To counter these threats, new satellite and ground systems are using cryptographic technologies to provide a range of services: confidentiality, entity & message authentication, and data integrity. Additionally, key management cryptographic services are required to support these services. This paper describes the key points of current satellite control and operations, that are authentication of the access to the satellite TMTC link and encryption of security relevant TM/TC data. For payload data management the key points are multi-user ground station access and high data rates both requiring frequent updates and uploads of keys with the corresponding key management methods. For secure satellite management authentication & key negotiation algorithms as HMAC-RIPEMD160, EC- DSA and EC-DH are used. Encryption of data uses algorithms as IDEA, AES, Triple-DES, or other. A channel coding and encryption unit for payload data provides download data rates up to Nx250 Mbps. The presented concepts are based on our experience and heritage of the security systems for all German MOD satellite projects (SATCOMBw2, SAR-Lupe multi- satellite system and German-French SAR-Lupe-Helios- II systems inter-operability) as well as for further international (KOMPSAT-II Payload data link system) and ESA activities (TMTC security and GMES).

  11. Network design consideration of a satellite-based mobile communications system

    Science.gov (United States)

    Yan, T.-Y.

    1986-01-01

    Technical considerations for the Mobile Satellite Experiment (MSAT-X), the ground segment testbed for the low-cost spectral efficient satellite-based mobile communications technologies being developed for the 1990's, are discussed. The Network Management Center contains a flexible resource sharing algorithm, the Demand Assigned Multiple Access scheme, which partitions the satellite transponder bandwidth among voice, data, and request channels. Satellite use of multiple UHF beams permits frequency reuse. The backhaul communications and the Telemetry, Tracking and Control traffic are provided through a single full-coverage SHF beam. Mobile Terminals communicate with the satellite using UHF. All communications including SHF-SHF between Base Stations and/or Gateways, are routed through the satellite. Because MSAT-X is an experimental network, higher level network protocols (which are service-specific) will be developed only to test the operation of the lowest three levels, the physical, data link, and network layers.

  12. Satellite communications principles and applications

    CERN Document Server

    Calcutt, David

    1994-01-01

    Satellites are increasingly used for global communications, as well as for radio and television transmissions. With the growth of mobile communications, and of digital technology, the use of satellite systems is set to expand substantially and already all students of electronics or communications engineering must study the subject.This book steers a middle path between offering a basic understanding of the process of communication by satellite and the methodology used; and the extensive mathematical analysis normally adopted in similar texts. It presents the basic concepts, using as mu

  13. Absence of satellites of asteroids

    International Nuclear Information System (INIS)

    Gehrels, T.; Drummond, J.D.; Levenson, N.A.

    1987-01-01

    The absence of satellites within 0.1-7.0 arcmin of minor planets noted in the present CCD imaging survey is judged consistent with previous theoretical studies of collisions in which it is held that satellites would have to be larger than about 30 km in order to be collisionally stable. In view of tidal stability, the only main belt asteroid satellites which could conceivably possess stability over eons are near-contact binaries. Any recent collisional debris would be chaotic and collisionally unstable. 15 references

  14. How long do satellites need to overlap? Evaluation of climate data stability from overlapping satellite records

    Science.gov (United States)

    Weatherhead, Elizabeth C.; Harder, Jerald; Araujo-Pradere, Eduardo A.; Bodeker, Greg; English, Jason M.; Flynn, Lawrence E.; Frith, Stacey M.; Lazo, Jeffrey K.; Pilewskie, Peter; Weber, Mark; Woods, Thomas N.

    2017-12-01

    Sensors on satellites provide unprecedented understanding of the Earth's climate system by measuring incoming solar radiation, as well as both passive and active observations of the entire Earth with outstanding spatial and temporal coverage. A common challenge with satellite observations is to quantify their ability to provide well-calibrated, long-term, stable records of the parameters they measure. Ground-based intercomparisons offer some insight, while reference observations and internal calibrations give further assistance for understanding long-term stability. A valuable tool for evaluating and developing long-term records from satellites is the examination of data from overlapping satellite missions. This paper addresses how the length of overlap affects the ability to identify an offset or a drift in the overlap of data between two sensors. Ozone and temperature data sets are used as examples showing that overlap data can differ by latitude and can change over time. New results are presented for the general case of sensor overlap by using Solar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM) and Solar Stellar Irradiance Comparison Experiment (SOLSTICE) solar irradiance data as an example. To achieve a 1 % uncertainty in estimating the offset for these two instruments' measurement of the Mg II core (280 nm) requires approximately 5 months of overlap. For relative drift to be identified within 0.1 % yr-1 uncertainty (0.00008 W m-2 nm-1 yr-1), the overlap for these two satellites would need to be 2.5 years. Additional overlap of satellite measurements is needed if, as is the case for solar monitoring, unexpected jumps occur adding uncertainty to both offsets and drifts; the additional length of time needed to account for a single jump in the overlap data may be as large as 50 % of the original overlap period in order to achieve the same desired confidence in the stability of the merged data set. Results presented here are directly

  15. Description of Simulated Small Satellite Operation Data Sets

    Science.gov (United States)

    Kulkarni, Chetan S.; Guarneros Luna, Ali

    2018-01-01

    A set of two BP930 batteries (Identified as PK31 and PK35) were operated continuously for a simulated satellite operation profile completion for single cycle. The battery packs were charged to an initial voltage of around 8.35 V for 100% SOC before the experiment was started. This document explains the structure of the battery data sets. Please cite this paper when using this dataset: Z. Cameron, C. Kulkarni, A. Guarneros, K. Goebel, S. Poll, "A Battery Certification Testbed for Small Satellite Missions", IEEE AUTOTESTCON 2015, Nov 2-5, 2015, National Harbor, MA

  16. Satellite tracking of threatened species

    Science.gov (United States)

    Williams, M.; Lunsford, A.; Ellis, D.; Robinson, J.; Coronado, P.; Campbell, W.

    1998-01-01

    In 1990, a joint effort of two U.S. federal agencies, NASA Goddard Space Flight Center (GSFC) and the Patuxent Wildlife Research Center, began. We initially joined forces in a project that used satellite telemetry to discover the winter home of a tiny dwindling population of Siberian Cranes. Since then several projects have emerged, and a web site was created to follow some of these activities. This web site is called the Satellite Tracking of Threatened Species and its location is http://sdcd.gsfc.nasa.gov/ISTO/satellite_tracking. It describes the overall program, and links you to three subsections that describe the projects in more detail: Satellite Direct Readout, Birdtracks, and Birdworld.

  17. Commercial satellite broadcasting for Europe

    Science.gov (United States)

    Forrest, J. R.

    1988-12-01

    A review is presented of the current television broadcasting situation in European countries, which involves a varied mix of terrestrial VHF or UHF systems and cable networks. A small market has emerged in Europe for receivers using the low-power telecommunications satellite transmission between the program providers and cable network companies. This is expected to change with the launch of medium-power pan-European telecommunication satellites (e.g. ASTRA, EUTELSAT II), which are now directly addressing the market of home reception. DBS (direct broadcast satellite) in the UK, using the D-MAC transmission standard, will offer three additional television channels, data broadcasting services, and a planned evolution to compatible forms of wide-screen, high-definition television. Comments are given on receiver and conditional access system standardization. Some views are expressed on satellite broadcasting as part of an overall broadcasting framework for the future.

  18. Small Satellite Mechanical Design Experience

    OpenAIRE

    Meyers, Stewart

    1993-01-01

    The design approach used and the experience gained in the building of four small satellite payloads is explained. Specific recommendations are made and the lessons learned on the SAMPEX program are detailed.

  19. Sea Turtle Satellite Telemetry Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sea turtles captured in various fishing gear (pound nets, long haul seines, gill nets) were outfitted with satellite transmitters so that their movements, migratory...

  20. Next generation satellite communications networks

    Science.gov (United States)

    Garland, P. J.; Osborne, F. J.; Streibl, I.

    The paper introduces two potential uses for new space hardware to permit enhanced levels of signal handling and switching in satellite communication service for Canada. One application involves increased private-sector services in the Ku band; the second supports new personal/mobile services by employing higher levels of handling and switching in the Ka band. First-generation satellite regeneration and switching experiments involving the NASA/ACTS spacecraft are described, where the Ka band and switching satellite network problems are emphasized. Second-generation satellite development is outlined based on demand trends for more packet-based switching, low-cost earth stations, and closed user groups. A demonstration mission for new Ka- and Ku-band technologies is proposed, including the payload configuration. The half ANIK E payload is shown to meet the demonstration objectives, and projected to maintain a fully operational payload for at least 10 years.

  1. Satellite Teleconferencing in the Caribbean.

    Science.gov (United States)

    Sankar, Hollis C.

    1985-01-01

    Discusses the need for, and the development, use, and future trends of, the University of the West Indies Distance Teaching Experiment, which utilizes telephone and communications satellite technology teleconferencing to extend educational opportunities to the peoples of the Caribbean. (MBR)

  2. The Educational Satellite in Perspective

    Science.gov (United States)

    Fraser, D. O.

    1975-01-01

    A discussion which contends that there is merit in not gearing satellite systems solely to educational broadcasting and that they should be designed for general communication, including telephony and television entertainment. (Author/HB)

  3. Existence of undiscovered Uranian satellites

    International Nuclear Information System (INIS)

    Boice, D.C.

    1986-04-01

    Structure in the Uranian ring system as observed in recent occultations may contain indirect evidence for the existence of undiscovered satellites. Using the Alfven and Arrhenius (1975, 1976) scenario for the formation of planetary systems, the orbital radii of up to nine hypothetical satellites interior to Miranda are computed. These calculations should provide interesting comparisons when the results from the Voyager 2 encounter with Uranus are made public. 15 refs., 1 fig., 1 tab

  4. Satellite medical centers project

    Science.gov (United States)

    Aggarwal, Arvind

    2002-08-01

    World class health care for common man at low affordable cost: anywhere, anytime The project envisages to set up a national network of satellite Medical centers. Each SMC would be manned by doctors, nurses and technicians, six doctors, six nurses, six technicians would be required to provide 24 hour cover, each SMC would operate 24 hours x 7 days. It would be equipped with the Digital telemedicine devices for capturing clinical patient information and investigations in the form of voice, images and data and create an audiovisual text file - a virtual Digital patient. Through the broad band connectivity the virtual patient can be sent to the central hub, manned by specialists, specialists from several specialists sitting together can view the virtual patient and provide a specialized opinion, they can see the virtual patient, see the examination on line through video conference or even PCs, talk to the patient and the doctor at the SMC and controlle capturing of information during examination and investigations of the patient at the SMC - thus creating a virtual Digital consultant at the SMC. Central hub shall be connected to the doctors and consultants in remote locations or tertiary care hospitals any where in the world, thus creating a virtual hub the hierarchical system shall provide upgradation of knowledge to thedoctors in central hub and smc and thus continued medical education and benefit the patient thru the world class treatment in the smc located at his door step. SMC shall be set up by franchisee who shall get safe business opportunity with high returns, patients shall get Low cost user friendly worldclass health care anywhere anytime, Doctors can get better meaningful selfemplyment with better earnings, flexibility of working time and place. SMC shall provide a wide variety of services from primary care to world class Global consultation for difficult patients.

  5. Spanish Earth Observation Satellite System

    Science.gov (United States)

    Borges, A.; Cerezo, F.; Fernandez, M.; Lomba, J.; Lopez, M.; Moreno, J.; Neira, A.; Quintana, C.; Torres, J.; Trigo, R.; Urena, J.; Vega, E.; Vez, E.

    2010-12-01

    The Spanish Ministry of Industry, Tourism and Trade (MITyC) and the Ministry of Defense (MoD) signed an agreement in 2007 for the development of a "Spanish Earth Observation Satellite System" based, in first instance, on two satellites: a high resolution optical satellite, called SEOSAT/Ingenio, and a radar satellite based on SAR technology, called SEOSAR/Paz. SEOSAT/Ingenio is managed by MITyC through the Centre for the Development of Industrial Technology (CDTI), with technical and contractual support from the European Space Agency (ESA). HISDESA T together with the Spanish Instituto Nacional de Técnica Aeroespacial (INTA, National Institute for Aerospace Technology) will be responsible for the in-orbit operation and the commercial operation of both satellites, and for the technical management of SEOSAR/Paz on behalf of the MoD. In both cases EADS CASA Espacio (ECE) is the prime contractor leading the industrial consortia. The ground segment development will be assigned to a Spanish consortium. This system is the most important contribution of Spain to the European Programme Global Monitoring for Environment and Security, GMES. This paper presents the Spanish Earth Observation Satellite System focusing on SEOSA T/Ingenio Programme and with special emphasis in the potential contribution to the ESA Third Party Missions Programme and to the Global Monitoring for Environment and Security initiative (GMES) Data Access.

  6. FORMATION OF MULTIPLE-SATELLITE SYSTEMS FROM LOW-MASS CIRCUMPLANETARY PARTICLE DISKS

    International Nuclear Information System (INIS)

    Hyodo, Ryuki; Ohtsuki, Keiji; Takeda, Takaaki

    2015-01-01

    Circumplanetary particle disks would be created in the late stage of planetary formation either by impacts of planetary bodies or disruption of satellites or passing bodies, and satellites can be formed by accretion of disk particles spreading across the Roche limit. Previous N-body simulation of lunar accretion focused on the formation of single-satellite systems from disks with large disk-to-planet mass ratios, while recent models of the formation of multiple-satellite systems from disks with smaller mass ratios do not take account of gravitational interaction between formed satellites. In the present work, we investigate satellite accretion from particle disks with various masses, using N-body simulation. In the case of accretion from somewhat less massive disks than the case of lunar accretion, formed satellites are not massive enough to clear out the disk, but can become massive enough to gravitationally shepherd the disk outer edge and start outward migration due to gravitational interaction with the disk. When the radial location of the 2:1 mean motion resonance of the satellite reaches outside the Roche limit, the second satellite can be formed near the disk outer edge, and then the two satellites continue outward migration while being locked in the resonance. Co-orbital satellites are found to be occasionally formed on the orbit of the first satellite. Our simulations also show that stochastic nature involved in gravitational interaction and collision between aggregates in the tidal environment can lead to diversity in the final mass and orbital architecture, which would be expected in satellite systems of exoplanets

  7. Satellites You Can See for Homework

    Science.gov (United States)

    Broderick, Stephen

    2012-01-01

    Artificial satellites are easily observed most nights when the weather is fine. The website called "Heavens Above" at www.heavens-above.com will help locate these satellites flying over one's location. It also includes how bright they will appear. The direction of travel of each satellite in the night sky also indicates the type of satellite. For…

  8. Analysis of raw AIS spectrum recordings from a LEO satellite

    DEFF Research Database (Denmark)

    Larsen, Jesper Abildgaard; Mortensen, Hans Peter

    2014-01-01

    The AAUSAT3 satellite is a 1U cubesat, which has been developed by students at Aalborg University, Denmark in collaboration with the Danish Maritime Authority. The satellite was launched in February 2013 on a mission to monitor ships from space using their AIS broadcast signals as an indication...... of position. The SDR receiver developed to listen for these AIS signals also allows for sampling and storing of the raw intermediate frequency spectrum, which has been used in order to map channel utilization over the areas of interest for the mission, which is mainly the arctic regions. The SDR based...... receiver used onboard the satellite is using a single chip front-end solution, which down converts the AIS signal located around 162 MHz into an intermediate frequency, with a up to 200 kHz bandwidth. This I/F signal is sampled with a 750 kSPS A/D converter and further processed by an Analog Devices DSP...

  9. Conceptual design of a synchronous Mars telecommunications satellite

    Science.gov (United States)

    Badi, Deborah M.; Farmer, Jeffrey T.; Garn, Paul A.; Martin, Gary L.

    1989-01-01

    Future missions to Mars will require a communications system to link activities on the Martian surface with each other and with mission controllers on Earth. A conceptual design is presented for an aerosynchronous communications satellite to provide these links. The satellite provides the capability for voice, data/command, and video transmissions. The mission scenario assumed for the design is described, and a description of a single aerosynchronous satellite is explained. A viable spacecraft design is then presented. Communication band selection and channel allocation are discussed. The communications system conceptual design is presented along with the trades used in sizing each of the required antennas. Also, the analyses used to develop the supporting subsystem designs are described as is the communications impact on each subsystem design.

  10. Shadow imaging of geosynchronous satellites

    Science.gov (United States)

    Douglas, Dennis Michael

    Geosynchronous (GEO) satellites are essential for modern communication networks. If communication to a GEO satellite is lost and a malfunction occurs upon orbit insertion such as a solar panel not deploying there is no direct way to observe it from Earth. Due to the GEO orbit distance of ~36,000 km from Earth's surface, the Rayleigh criteria dictates that a 14 m telescope is required to conventionally image a satellite with spatial resolution down to 1 m using visible light. Furthermore, a telescope larger than 30 m is required under ideal conditions to obtain spatial resolution down to 0.4 m. This dissertation evaluates a method for obtaining high spatial resolution images of GEO satellites from an Earth based system by measuring the irradiance distribution on the ground resulting from the occultation of the satellite passing in front of a star. The representative size of a GEO satellite combined with the orbital distance results in the ground shadow being consistent with a Fresnel diffraction pattern when observed at visible wavelengths. A measurement of the ground shadow irradiance is used as an amplitude constraint in a Gerchberg-Saxton phase retrieval algorithm that produces a reconstruction of the satellite's 2D transmission function which is analogous to a reverse contrast image of the satellite. The advantage of shadow imaging is that a terrestrial based redundant set of linearly distributed inexpensive small telescopes, each coupled to high speed detectors, is a more effective resolved imaging system for GEO satellites than a very large telescope under ideal conditions. Modeling and simulation efforts indicate sub-meter spatial resolution can be readily achieved using collection apertures of less than 1 meter in diameter. A mathematical basis is established for the treatment of the physical phenomena involved in the shadow imaging process. This includes the source star brightness and angular extent, and the diffraction of starlight from the satellite

  11. Earth-satellite propagation above GHz: Papers from the 1972 spring URSI session on experiments utilizing the ATS-5 satellite

    Science.gov (United States)

    Ippolito, L. J. (Compiler)

    1972-01-01

    Papers are reported from the Special Session on Earth-Satellite Propagation Above 10 GHz, presented at The 1972 Spring Meeting of the United States National Committee, International Union of Radio Science, April 1972, Washington, D. C. This session was devoted to propagation measurements associated with the Applications Technology Satellite (ATS-5), which provided the first operational earth-space links at frequencies above 15 GHz. A comprehensive summary is presented of the major results of the ATS-5 experiment measurements and related radiometric, radar and meteorological studies. The papers are organized around seven selected areas of interest, with the results of the various investigators combined into a single paper presented by a principal author for that area. A comprehensive report is provided on the results of the ATS-5 satellite to earth transmissions. A complete list of published reports and presentations related to the ATS-5 Millimeter Wave Experiment is included.

  12. Choosing ESRO's first scientific satellites

    Science.gov (United States)

    Russo, Arturo

    1992-11-01

    The choice of the scientific payloads of the European Space Research Organization's (ESRO's) first generation of satellites is analyzed. Concentration is on those aspects of the decision process that involved more directly the scientific community and that emerged as major issues in the discussion of the Launching Program Advisory Committee (LPAC). The main theme was the growing competition between the various fields of space science within the progressive retrenching of the Organization's financial resources available for the satellite program. A general overview of the status of the program by the end of 1966 is presented. The choice of the first small satellites' payloads (ESRO 1 and 2, and HEOS-A) and the difficult definition of the TD satellite program are discussed. This part covers a time span going from early 1963 to the spring of 1966. In the second part, the narrative starts from the spring of 1967, when the decision to recommend a second HEOS-type satellite was taken, and then analyzes the complex situation determined by the crisis of the TD program in 1968, and the debates which eventually led to the abandonment of TD-2 and the start of the far less ambitious ESRO 5 project.

  13. Physical characteristics of satellite surfaces

    International Nuclear Information System (INIS)

    Veverka, J.; Thomas, P.; Johnson, T.V.; Matson, D.; Housen, K.

    1986-01-01

    Both exogenic and endogenic effects have been proposed to explain the major observed characteristics of satellite surfaces. The current view is that the basic properties of most surfaces result from the intrinsic composition of a body and its geologic history. Exogenic effects have, however, played a role in modifying the appearance of nearly all surfaces. The most important exogenic effect is impact cratering, one manifestation of which is the production of micrometeoroid gardened regoliths on airless bodies. On large, silicate bodies the micrometeoroid bombardment can produce an optically mature, dark agglutinate-rich soil; the nature of regoliths on predominantly icy satellites remains uncertain. Direct accumulation of infalling material does not appear to play a major role in modifying most surfaces. Solar wind radiation effects have not altered greatly the optical properties of solar system objects; magnetospheric charged particles may have modified the optical properties of some outer planet satellites (e.g., sulfur ion bombardment in the case of some of the satellites of Jupiter). Other effects, such as aeolian and liquid/solid chemical weathering, may be important on satellites with atmospheres like Titan and Triton

  14. Chartering Launchers for Small Satellites

    Science.gov (United States)

    Hernandez, Daniel

    The question of how to launch small satellites has been solved over the years by the larger launchers offering small satellites the possibility of piggy-backing. Specific fixtures have been developed and commercialized: Arianespace developed the ASAP interface, the USAF studied ESPA, NASA has promoted Shuttle launch possibilities, Russian authorities and companies have been able to find solutions with many different launchers... It is fair to say that most launcher suppliers have worked hard and finally often been able to find solutions to launch most small satellites into orbit. It is also true, however, that most of these small satellites were technology demonstration missions capable of accepting a wide range of orbit and launch characteristics: orbit altitude and inclination, launch date, etc. In some cases the small satellite missions required a well-defined type of orbit and have therefore been obliged to hire a small launcher on which they were the prime passenger. In our paper we would like to propose an additional solution to all these possibilities: launchers could plan well in advance (for example about 3 years), trips to precisely defined orbits to allow potential passengers to organize themselves and be ready on the D-Day. On the scheduled date the chartered launcher goes to the stated orbit while on another date, another chartered launcher goes to another orbit. The idea is to organize departures for space like trains or airplanes leaving on known schedules for known destinations.

  15. Satellite Cell Self-Renewal.

    Science.gov (United States)

    Giordani, Lorenzo; Parisi, Alice; Le Grand, Fabien

    2018-01-01

    Adult skeletal muscle is endowed with regenerative potential through partially recapitulating the embryonic developmental program. Upon acute injury or in pathological conditions, quiescent muscle-resident stem cells, called satellite cells, become activated and give rise to myogenic progenitors that massively proliferate, differentiate, and fuse to form new myofibers and restore tissue functionality. In addition, a proportion of activated cells returns back to quiescence and replenish the pool of satellite cells in order to maintain the ability of skeletal muscle tissue to repair. Self-renewal is the process by which stem cells divide to make more stem cells to maintain the stem cell population throughout life. This process is controlled by cell-intrinsic transcription factors regulated by cell-extrinsic signals from the niche and the microenvironment. This chapter provides an overview about the general aspects of satellite cell biology and focuses on the cellular and molecular aspects of satellite cell self-renewal. To date, we are still far from understanding how a very small proportion of the satellite cell progeny maintain their stem cell identity when most of their siblings progress through the myogenic program to construct myofibers. © 2018 Elsevier Inc. All rights reserved.

  16. Satellite DNA: An Evolving Topic.

    Science.gov (United States)

    Garrido-Ramos, Manuel A

    2017-09-18

    Satellite DNA represents one of the most fascinating parts of the repetitive fraction of the eukaryotic genome. Since the discovery of highly repetitive tandem DNA in the 1960s, a lot of literature has extensively covered various topics related to the structure, organization, function, and evolution of such sequences. Today, with the advent of genomic tools, the study of satellite DNA has regained a great interest. Thus, Next-Generation Sequencing (NGS), together with high-throughput in silico analysis of the information contained in NGS reads, has revolutionized the analysis of the repetitive fraction of the eukaryotic genomes. The whole of the historical and current approaches to the topic gives us a broad view of the function and evolution of satellite DNA and its role in chromosomal evolution. Currently, we have extensive information on the molecular, chromosomal, biological, and population factors that affect the evolutionary fate of satellite DNA, knowledge that gives rise to a series of hypotheses that get on well with each other about the origin, spreading, and evolution of satellite DNA. In this paper, I review these hypotheses from a methodological, conceptual, and historical perspective and frame them in the context of chromosomal organization and evolution.

  17. Space Solar Power: Satellite Concepts

    Science.gov (United States)

    Little, Frank E.

    1999-01-01

    Space Solar Power (SSP) applies broadly to the use of solar power for space related applications. The thrust of the NASA SSP initiative is to develop concepts and demonstrate technology for applying space solar power to NASA missions. Providing power from satellites in space via wireless transmission to a receiving station either on earth, another celestial body or a second satellite is one goal of the SSP initiative. The sandwich design is a satellite design in which the microwave transmitting array is the front face of a thin disk and the back of the disk is populated with solar cells, with the microwave electronics in between. The transmitter remains aimed at the earth in geostationary orbit while a system of mirrors directs sunlight to the photovoltaic cells, regardless of the satellite's orientation to the sun. The primary advantage of the sandwich design is it eliminates the need for a massive and complex electric power management and distribution system for the satellite. However, it requires a complex system for focusing sunlight onto the photovoltaic cells. In addition, positioning the photovoltaic array directly behind the transmitting array power conversion electronics will create a thermal management challenge. This project focused on developing designs and finding emerging technology to meet the challenges of solar tracking, a concentrating mirror system including materials and coatings, improved photovoltaic materials and thermal management.

  18. Advanced technologies for encryption of satellite links

    Science.gov (United States)

    McMahan, Sherry S.

    The use of encryption on satellite links is discussed. Advanced technology exists to provide transmission security for large earth station with data rates up to 50 megabits per second. One of the major concerns in the use of encryption equipment with very small aperture terminals (VSAT) is the key management issue and the related operational costs. The low cost requirement and the lack of physical protection of remote VSATs place severe constraints on the design of encryption equipment. Encryption may be accomplished by embedding a tamper proof encryption module into the baseband unit of each VSAT. VSAT networks are usually star networks where there is a single large earth station that serves as a hub and all satellite communications takes place between each VSAT and the hub earth station. The hub earth station has the secret master key of each VSAT. These master keys are used to downline load encrypted session keys to each VSAT. A more secure alternative is to use public key techniques where each embedded VSAT encryption module internally generates its own secret and public numbers. The secret number never leaves the module while the public number is sent to the hub at the time of initialization of the encryption module into the VSAT. Physical access control to encryption modules of VSAT systems can be implemented using passwords, smart cards or biometrics.

  19. The Advanced Communication Technology Satellite and ISDN

    Science.gov (United States)

    Lowry, Peter A.

    1996-01-01

    This paper depicts the Advanced Communication Technology Satellite (ACTS) system as a global central office switch. The ground portion of the system is the collection of earth stations or T1-VSAT's (T1 very small aperture terminals). The control software for the T1-VSAT's resides in a single CPU. The software consists of two modules, the modem manager and the call manager. The modem manager (MM) controls the RF modem portion of the T1-VSAT. It processes the orderwires from the satellite or from signaling generated by the call manager (CM). The CM controls the Recom Laboratories MSPs by receiving signaling messages from the stacked MSP shelves ro units and sending appropriate setup commands to them. There are two methods used to setup and process calls in the CM; first by dialing up a circuit using a standard telephone handset or, secondly by using an external processor connected to the CPU's second COM port, by sending and receiving signaling orderwires. It is the use of the external processor which permits the ISDN (Integrated Services Digital Network) Signaling Processor to implement ISDN calls. In August 1993, the initial testing of the ISDN Signaling Processor was carried out at ACTS System Test at Lockheed Marietta, Princeton, NJ using the spacecraft in its test configuration on the ground.

  20. Skeletal Muscle Satellite Cells Are Committed to Myogenesis and Do Not Spontaneously Adopt Nonmyogenic Fates

    Science.gov (United States)

    Starkey, Jessica D.; Yamamoto, Masakazu; Yamamoto, Shoko; Goldhamer, David J.

    2011-01-01

    The developmental potential of skeletal muscle stem cells (satellite cells) remains controversial. The authors investigated satellite cell developmental potential in single fiber and clonal cultures derived from MyoDiCre/+;R26REYFP/+ muscle, in which essentially all satellite cells are permanently labeled. Approximately 60% of the clones derived from cells that co-purified with muscle fibers spontaneously underwent adipogenic differentiation. These adipocytes stained with Oil-Red-O and expressed the terminal differentiation markers, adipsin and fatty acid binding protein 4, but did not express EYFP and were therefore not of satellite cell origin. Satellite cells mutant for either MyoD or Myf-5 also maintained myogenic programming in culture and did not adopt an adipogenic fate. Incorporation of additional wash steps prior to muscle fiber plating virtually eliminated the non-myogenic cells but did not reduce the number of adherent Pax7+ satellite cells. More than half of the adipocytes observed in cultures from Tie2-Cre mice were recombined, further demonstrating a non-satellite cell origin. Under adipogenesis-inducing conditions, satellite cells accumulated cytoplasmic lipid but maintained myogenic protein expression and did not fully execute the adipogenic differentiation program, distinguishing them from adipocytes observed in muscle fiber cultures. The authors conclude that skeletal muscle satellite cells are committed to myogenesis and do not spontaneously adopt an adipogenic fate. PMID:21339173

  1. Validation of Galileo orbits using SLR with a focus on satellites launched into incorrect orbital planes

    Science.gov (United States)

    Sośnica, Krzysztof; Prange, Lars; Kaźmierski, Kamil; Bury, Grzegorz; Drożdżewski, Mateusz; Zajdel, Radosław; Hadas, Tomasz

    2018-02-01

    The space segment of the European Global Navigation Satellite System (GNSS) Galileo consists of In-Orbit Validation (IOV) and Full Operational Capability (FOC) spacecraft. The first pair of FOC satellites was launched into an incorrect, highly eccentric orbital plane with a lower than nominal inclination angle. All Galileo satellites are equipped with satellite laser ranging (SLR) retroreflectors which allow, for example, for the assessment of the orbit quality or for the SLR-GNSS co-location in space. The number of SLR observations to Galileo satellites has been continuously increasing thanks to a series of intensive campaigns devoted to SLR tracking of GNSS satellites initiated by the International Laser Ranging Service. This paper assesses systematic effects and quality of Galileo orbits using SLR data with a main focus on Galileo satellites launched into incorrect orbits. We compare the SLR observations with respect to microwave-based Galileo orbits generated by the Center for Orbit Determination in Europe (CODE) in the framework of the International GNSS Service Multi-GNSS Experiment for the period 2014.0-2016.5. We analyze the SLR signature effect, which is characterized by the dependency of SLR residuals with respect to various incidence angles of laser beams for stations equipped with single-photon and multi-photon detectors. Surprisingly, the CODE orbit quality of satellites in the incorrect orbital planes is not worse than that of nominal FOC and IOV orbits. The RMS of SLR residuals is even lower by 5.0 and 1.5 mm for satellites in the incorrect orbital planes than for FOC and IOV satellites, respectively. The mean SLR offsets equal -44.9, -35.0, and -22.4 mm for IOV, FOC, and satellites in the incorrect orbital plane. Finally, we found that the empirical orbit models, which were originally designed for precise orbit determination of GNSS satellites in circular orbits, provide fully appropriate results also for highly eccentric orbits with variable linear

  2. Gaussian entanglement distribution via satellite

    Science.gov (United States)

    Hosseinidehaj, Nedasadat; Malaney, Robert

    2015-02-01

    In this work we analyze three quantum communication schemes for the generation of Gaussian entanglement between two ground stations. Communication occurs via a satellite over two independent atmospheric fading channels dominated by turbulence-induced beam wander. In our first scheme, the engineering complexity remains largely on the ground transceivers, with the satellite acting simply as a reflector. Although the channel state information of the two atmospheric channels remains unknown in this scheme, the Gaussian entanglement generation between the ground stations can still be determined. On the ground, distillation and Gaussification procedures can be applied, leading to a refined Gaussian entanglement generation rate between the ground stations. We compare the rates produced by this first scheme with two competing schemes in which quantum complexity is added to the satellite, thereby illustrating the tradeoff between space-based engineering complexity and the rate of ground-station entanglement generation.

  3. Advanced satellite servicing facility studies

    Science.gov (United States)

    Qualls, Garry D.; Ferebee, Melvin J., Jr.

    1988-01-01

    A NASA-sponsored systems analysis designed to identify and recommend advanced subsystems and technologies specifically for a manned Sun-synchronous platform for satellite management is discussed. An overview of system design, manned and unmanned servicing facilities, and representative mission scenarios are given. Mission areas discussed include facility based satellite assembly, checkout, deployment, refueling, repair, and systems upgrade. The ferrying of materials and consumables to and from manufacturing platforms, deorbit, removal, repositioning, or salvage of satellites and debris, and crew rescue of any other manned vehicles are also examined. Impacted subsytems discussed include guidance navigation and control, propulsion, data management, power, thermal control, structures, life support, and radiation management. In addition, technology issues which would have significant impacts on the system design are discussed.

  4. Small satellites and their regulation

    CERN Document Server

    Jakhu, Ram S

    2014-01-01

    Since the launch of UoSat-1 of the University of Surrey (United Kingdom) in 1981, small satellites proved regularly to be useful, beneficial, and cost-effective tools. Typical tasks cover education and workforce development, technology demonstration, verification and validation, scientific and engineering research as well as commercial applications. Today the launch masses range over almost three orders of magnitude starting at less than a kilogram up to a few hundred kilograms, with budgets of less than US$ 100.00 and up to millions within very short timeframes of sometimes less than two years. Therefore each category of small satellites provides specific challenges in design, development and operations. Small satellites offer great potentials to gain responsive, low-cost access to space within a short timeframe for institutions, companies, regions and countries beyond the traditional big players in the space arena. For these reasons (particularly the low cost of construction, launch and operation), small (m...

  5. Satellite Communications Using Commercial Protocols

    Science.gov (United States)

    Ivancic, William D.; Griner, James H.; Dimond, Robert; Frantz, Brian D.; Kachmar, Brian; Shell, Dan

    2000-01-01

    NASA Glenn Research Center has been working with industry, academia, and other government agencies in assessing commercial communications protocols for satellite and space-based applications. In addition, NASA Glenn has been developing and advocating new satellite-friendly modifications to existing communications protocol standards. This paper summarizes recent research into the applicability of various commercial standard protocols for use over satellite and space- based communications networks as well as expectations for future protocol development. It serves as a reference point from which the detailed work can be readily accessed. Areas that will be addressed include asynchronous-transfer-mode quality of service; completed and ongoing work of the Internet Engineering Task Force; data-link-layer protocol development for unidirectional link routing; and protocols for aeronautical applications, including mobile Internet protocol routing for wireless/mobile hosts and the aeronautical telecommunications network protocol.

  6. Landsat—Earth observation satellites

    Science.gov (United States)

    ,

    2015-11-25

    Since 1972, Landsat satellites have continuously acquired space-based images of the Earth’s land surface, providing data that serve as valuable resources for land use/land change research. The data are useful to a number of applications including forestry, agriculture, geology, regional planning, and education. Landsat is a joint effort of the U.S. Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA). NASA develops remote sensing instruments and the spacecraft, then launches and validates the performance of the instruments and satellites. The USGS then assumes ownership and operation of the satellites, in addition to managing all ground reception, data archiving, product generation, and data distribution. The result of this program is an unprecedented continuing record of natural and human-induced changes on the global landscape.

  7. Resonant satellite transitions in argon

    International Nuclear Information System (INIS)

    Samson, J.A.R.; Lee Eunmee; Chung, Y.

    1990-01-01

    The production of specific Ar + satellite states has been studied with synchrotron radiation at wavelengths between 300 and 350 A with an effective energy resolution of 20 meV. The specific states studied were the ( 3 P)4p( 2 P 3/2 ), ( 1 D)4p( 2 F 7/2 ), and ( 1 D)4p( 2 P 1/2 ) states. The fluorescent radiation emitted from these excited ionic states was measured at 4766, 4611, and 4133 A by the use of narrow band interference filters. The variation of the fluorescence intensity was measured as a function of wavelength. This provided a measure of the relative cross section for production of the satellite states. Each satellite state was found to be completely dominated by autoionization of the neutral doubly excited states (3s 2 3p 4 )nl, n'l' found in this spectral region. (orig.)

  8. Dust aerosol impact on North Africa climate: a GCM investigation of aerosol-cloud-radiation interactions using A-Train satellite data

    Directory of Open Access Journals (Sweden)

    Y. Gu

    2012-02-01

    Full Text Available The climatic effects of dust aerosols in North Africa have been investigated using the atmospheric general circulation model (AGCM developed at the University of California, Los Angeles (UCLA. The model includes an efficient and physically based radiation parameterization scheme developed specifically for application to clouds and aerosols. Parameterization of the effective ice particle size in association with the aerosol first indirect effect based on ice cloud and aerosol data retrieved from A-Train satellite observations have been employed in climate model simulations. Offline simulations reveal that the direct solar, IR, and net forcings by dust aerosols at the top of the atmosphere (TOA generally increase with increasing aerosol optical depth. When the dust semi-direct effect is included with the presence of ice clouds, positive IR radiative forcing is enhanced since ice clouds trap substantial IR radiation, while the positive solar forcing with dust aerosols alone has been changed to negative values due to the strong reflection of solar radiation by clouds, indicating that cloud forcing associated with aerosol semi-direct effect could exceed direct aerosol forcing. With the aerosol first indirect effect, the net cloud forcing is generally reduced in the case for an ice water path (IWP larger than 20 g m−2. The magnitude of the reduction increases with IWP.

    AGCM simulations show that the reduced ice crystal mean effective size due to the aerosol first indirect effect results in less OLR and net solar flux at TOA over the cloudy area of the North Africa region because ice clouds with smaller size trap more IR radiation and reflect more solar radiation. The precipitation in the same area, however, increases due to the aerosol indirect effect on ice clouds, corresponding to the enhanced convection as indicated by reduced OLR. Adding the aerosol direct effect into the model simulation reduces the precipitation in the

  9. Satellite communications: possibilities and problems

    International Nuclear Information System (INIS)

    Hine, M.

    1986-01-01

    Communication links via satellites are becoming available in Europe, both as part of the development of the telephone system and as special services aimed at data traffic. They offer the possibility of speeds between 50 kb/s and 2 Mb/s, without the problems and long term commitments of long distance land lines. Such links are provided by the PTT's as circuits which can be booked for variable periods, and have error rates which can be very low and well controlled. Problems in networking can arise from the satellite delay, particularly if errors occur in the local connections, and from the leased circuit and tariff philosophies of the PTT's. (Auth.)

  10. 3D CAPABILITIES OF PLEIADES SATELLITE

    Directory of Open Access Journals (Sweden)

    M. Bernard

    2012-08-01

    Full Text Available End of 2011 a new optical satellite, called Pléiades, was launched by the French space agency (CNES. It provides 20 km x 20 km images at 0.5 meters. This agile acquisition system is able to relocate very rapidly and scan the earth in any direction. The agility of the system offers the ability to acquire multi viewing angle images of the same area during the same orbit. This ability to capture, from a single stereoscopic pair, to a sequence of 25 images, allows enhancing the quality and the completeness of automatically extracted 3D maps. The aim of the study is to validate and quantify the capacity of the Pléiades system to perform 3D mapping. The analysis explores the advantages in terms of quality and automatism to use more than 2 stereoscopic images. In the last 10 years, automatic 3D processing of digital images became more and more popular and efficient. Thanks to aerial images with very large overlap and very high resolution satellite images, new methodologies and algorithms have been implemented to improve the quality and accuracy of automatic 3D processing. We propose to experiment the same type of approaches using Pléiades images to produce digital elevation models (DEM. A focus is made on analysing the 3D processing using video like (multi viewing acquisitions. Different reference sites with very accurate 3D control points are used to quantify the quality of the Pléiades DEM. Different acquisition modes are explored from a single stereo pair to a sequence of 17 images.

  11. International Telecommunications Satellite Organization (INTELSAT) Agreement Between the United States of American and Other Governments and Operating Agreement.

    Science.gov (United States)

    Department of State, Washington, DC.

    The INTELSAT (International Telecommunications Satellite) agreement was reached because of the desirability of continuing the development of a telecommunications satellite system. INTELSAT's aim was to achieve a single global commercial system as part of an improved global telecommunications network which will provide expanded services to all…

  12. Satellite constellation design and radio resource management using genetic algorithm.

    OpenAIRE

    Asvial, Muhamad.

    2003-01-01

    A novel strategy for automatic satellite constellation design with satellite diversity is proposed. The automatic satellite constellation design means some parameters of satellite constellation design can be determined simultaneously. The total number of satellites, the altitude of satellite, the angle between planes, the angle shift between satellites and the inclination angle are considered for automatic satellite constellation design. Satellite constellation design is modelled using a mult...

  13. Online Visualization and Analysis of Global Half-Hourly Infrared Satellite Data

    Science.gov (United States)

    Liu, Zhong; Ostrenga, Dana; Leptoukh, Gregory

    2011-01-01

    nfrared (IR) images (approximately 11-micron channel) recorded by satellite sensors have been widely used in weather forecasting, research, and classroom education since the Nimbus program. Unlike visible images, IR imagery can reveal cloud features without sunlight illumination; therefore, they can be used to monitor weather phenomena day and night. With geostationary satellites deployed around the globe, it is possible to monitor weather events 24/7 at a temporal resolution that polar-orbiting satellites cannot achieve at the present time. When IR data from multiple geostationary satellites are merged to form a single product--also known as a merged product--it allows for observing weather on a global scale. Its high temporal resolution (e.g., every half hour) also makes it an ideal ancillary dataset for supporting other satellite missions, such as the Tropical Rainfall Measuring Mission (TRMM), etc., by providing additional background information about weather system evolution.

  14. Monitoring of rain water storage in forests with satellite radar

    OpenAIRE

    de Jong, JJM; Klaassen, W; Kuiper, PJC

    2002-01-01

    The sensitivity of radar backscatter to the amount of intercepted rain in temperate deciduous forests is analyzed to determine the feasibility of retrieval of this parameter from satellite radar data. A backscatter model is validated with X-band radar measurements of a single tree exposed to rain. A good agreement between simulation and measurements is observed and this demonstrates the ability of radar to measure the amount of intercepted rain. The backscatter model is next applied to simula...

  15. Satellite monitoring of black bear.

    Science.gov (United States)

    Craighead, J. J.; Craighead, F. C., Jr.; Varney, J. R.; Cote, C. E.

    1971-01-01

    Description of a feasibility experiment recently performed to test the use of a satellite system for telemetering environmental and physiological data from the winter den of a 'hibernating' black bear, Ursus americanus. The instrumentation procedure and evaluations of the equipment performance and sensory data obtained are discussed in detail.

  16. Atmospheric correction of satellite data

    Science.gov (United States)

    Shmirko, Konstantin; Bobrikov, Alexey; Pavlov, Andrey

    2015-11-01

    Atmosphere responses for more than 90% of all radiation measured by satellite. Due to this, atmospheric correction plays an important role in separating water leaving radiance from the signal, evaluating concentration of various water pigments (chlorophyll-A, DOM, CDOM, etc). The elimination of atmospheric intrinsic radiance from remote sensing signal referred to as atmospheric correction.

  17. Audio Satellites: Overhearing Everyday Life

    DEFF Research Database (Denmark)

    Kirkegaard, Jonas Rasmussen; Breinbjerg, M.; Højlund, M. K.

    2017-01-01

    around or displaced arbitrarily in a given landscape. In the web browser, the different sound streams from the individual satellites can be mixed together to form a cooperative soundscape. The project thus allows people to tune into and explore the overheard soundscape of everyday life in a collaborative...

  18. Electrophotometric observations of artificial satellites

    International Nuclear Information System (INIS)

    Vovchyk, Yeva; Blagodyr, Yaroslav; Kraynyuk, Gennadiy; Bilinsky, Andriy; Lohvynenko, Alexander; Klym, Bogdan; Pochapsky, Yevhen

    2004-01-01

    Problems associated with polarimetric observations of low Earth orbit artificial satellites as important solar system objects are discussed. The instrumentation (the optical and mechanical parts, the control and drive electronics, and the application software) for performing such observations is also described

  19. The Mobile Satellite Services Market.

    Science.gov (United States)

    Anderson, Samuel

    Mobile satellite (MSAT) technology is the basis for a new component of the telecommunications industry capable of providing services to small inexpensive subscriber terminals located almost any place in the world. The market for MSAT space segment capacity (bandwidth and power) is a natural monopoly that can be logically and technically…

  20. Launching the First Indian Satellite

    Indian Academy of Sciences (India)

    long run, this is not bad since it generates self-confidence and self-reliance - which in the final analysis are .... hopes to find some new X-ray sources. The second ... from the state of health of the satellite can be judged. A tracking network gives ...

  1. GOES-R: Satellite Insight

    Science.gov (United States)

    Fitzpatrick, Austin J.; Leon, Nancy J.; Novati, Alexander; Lincoln, Laura K.; Fisher, Diane K.

    2012-01-01

    GOES-R: Satellite Insight seeks to bring awareness of the GOES-R (Geostationary Operational Environmental Satellite -- R Series) satellite currently in development to an audience of all ages on the emerging medium of mobile games. The iPhone app (Satellite Insight) was created for the GOES-R Program. The app describes in simple terms the types of data products that can be produced from GOES-R measurements. The game is easy to learn, yet challenging for all audiences. It includes educational content and a path to further information about GOESR, its technology, and the benefits of the data it collects. The game features action-puzzle game play in which the player must prevent an overflow of data by matching falling blocks that represent different types of GOES-R data. The game adds more different types of data blocks over time, as long as the player can prevent a data overflow condition. Points are awarded for matches, and players can compete with themselves to beat their highest score.

  2. University Satellite Campus Management Models

    Science.gov (United States)

    Fraser, Doug; Stott, Ken

    2015-01-01

    Among the 60 or so university satellite campuses in Australia are many that are probably failing to meet the high expectations of their universities and the communities they were designed to serve. While in some cases this may be due to the demand driven system, it may also be attributable in part to the ways in which they are managed. The…

  3. Water Quality Monitoring by Satellite

    Science.gov (United States)

    Journal of Chemical Education, 2004

    2004-01-01

    The availability of abundant water resources in the Upper Midwest of the United States is nullified by their contamination through heavy commercial and industrial activities. Scientists have taken the responsibility of detecting the water quality of these resources through remote-sensing satellites to develop a wide-ranging water purification plan…

  4. Initial Assessment of Cyclone Global Navigation Satellite System (CYGNSS) Observations

    Science.gov (United States)

    McKague, D. S.; Ruf, C. S.

    2017-12-01

    The NASA Cyclone Global Navigation Satellite System (CYNSS) mission provides high temporal resolution observations of cyclones from a constellation of eight low-Earth orbiting satellites. Using the relatively new technique of Global Navigation Satellite System reflectometry (GNSS-R), all-weather observations are possible, penetrating even deep convection within hurricane eye walls. The compact nature of the GNSS-R receivers permits the use of small satellites, which in turn enables the launch of a constellation of satellites from a single launch vehicle. Launched in December of 2016, the eight CYGNSS satellites provide 25 km resolution observations of mean square slope (surface roughness) and surface winds with a 2.8 hour median revisit time from 38 S to 38 N degrees latitude. In addition to the calibration and validation of CYGNSS sea state observations, the CYGNSS science team is assessing the ability of the mission to provide estimates of cyclone size, intensity, and integrated kinetic energy. With its all-weather ability and high temporal resolution, the CYGNSS mission will add significantly to our ability to monitor cyclone genesis and intensification and will significantly reduce uncertainties in our ability to estimate cyclone intensity, a key variable in predicting its destructive potential. Members of the CYGNSS Science Team are also assessing the assimilation of CYGNSS data into hurricane forecast models to determine the impact of the data on forecast skill, using the data to study extra-tropical cyclones, and looking at connections between tropical cyclones and global scale weather, including the global hydrologic cycle. This presentation will focus on the assessment of early on-orbit observations of cyclones with respect to these various applications.

  5. Satellite-Based Precipitation Datasets

    Science.gov (United States)

    Munchak, S. J.; Huffman, G. J.

    2017-12-01

    Of the possible sources of precipitation data, those based on satellites provide the greatest spatial coverage. There is a wide selection of datasets, algorithms, and versions from which to choose, which can be confusing to non-specialists wishing to use the data. The International Precipitation Working Group (IPWG) maintains tables of the major publicly available, long-term, quasi-global precipitation data sets (http://www.isac.cnr.it/ ipwg/data/datasets.html), and this talk briefly reviews the various categories. As examples, NASA provides two sets of quasi-global precipitation data sets: the older Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) and current Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM) mission (IMERG). Both provide near-real-time and post-real-time products that are uniformly gridded in space and time. The TMPA products are 3-hourly 0.25°x0.25° on the latitude band 50°N-S for about 16 years, while the IMERG products are half-hourly 0.1°x0.1° on 60°N-S for over 3 years (with plans to go to 16+ years in Spring 2018). In addition to the precipitation estimates, each data set provides fields of other variables, such as the satellite sensor providing estimates and estimated random error. The discussion concludes with advice about determining suitability for use, the necessity of being clear about product names and versions, and the need for continued support for satellite- and surface-based observation.

  6. Satellite Tags- Guam/CNMI EEZ

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Satellite tagging was implemented in 2013. Satellite tagging is conducted using a Dan Inject air rifle and deployment arrows designed by Wildlife Computers. Two...

  7. New Equipment Training Center-Satellite Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The ARDEC Satellite Facility is a 24-hour on-site military satellite transmission and downlink capability to Southwest Asia and all other military OCONUS and CONUS...

  8. Some European capabilities in satellite cinema exhibition

    Science.gov (United States)

    Bock, Wolfgang

    1990-08-01

    The likely performance envelope and architecture for satellite cinema systems are derived from simple practical assumptions. A case is made for possible transatlantic cooperation towards establishing a satellite cinema standard.

  9. Multiple Usage of Existing Satellite Sensors (PREPRINT)

    National Research Council Canada - National Science Library

    Keeney, James T

    2006-01-01

    .... Space offers a near-perfect vacuum to operate a passive or active sensor. Volume, mass and power on satellites is limited and risk management approaches tended to remove such sensors from satellite systems...

  10. Multiple Usage of Existing Satellite Sensors

    National Research Council Canada - National Science Library

    Keeney, James T

    2006-01-01

    .... Space offers a near-perfect vacuum to operate a passive or active sensor. Volume, mass and power on satellites is limited and risk management approaches tended to remove such sensors from satellite systems...

  11. Biophysical applications of satellite remote sensing

    CERN Document Server

    Hanes, Jonathan

    2014-01-01

    Including an introduction and historical overview of the field, this comprehensive synthesis of the major biophysical applications of satellite remote sensing includes in-depth discussion of satellite-sourced biophysical metrics such as leaf area index.

  12. Core Flight System Satellite Starter Kit

    Data.gov (United States)

    National Aeronautics and Space Administration — The Core Flight System Satellite Starter Kit (cFS Kit) will allow a small satellite or CubeSat developer to rapidly develop, deploy, test, and operate flight...

  13. RFP for the italien satellite AGILE

    DEFF Research Database (Denmark)

    Madsen, Peter Buch; Jørgensen, John Leif; Riis, Troels

    1999-01-01

    The document descibes the ASC Star Tracker (performance, functionality, requirements etc.) to the Italian satellite AGILE.......The document descibes the ASC Star Tracker (performance, functionality, requirements etc.) to the Italian satellite AGILE....

  14. Highly Enhanced Risk Management Emergency Satellite

    DEFF Research Database (Denmark)

    Dalmeir, Michael; Gataullin, Yunir; Indrajit, Agung

    HERMES (Highly Enhanced Risk Management Emergency Satellite) is potential European satellite mission for global flood management, being implemented by Technical University Munich and European Space Agency. With its main instrument - a reliable and precise Synthetic Aperture Radar (SAR) antenna...

  15. Coverage Extension via Side-Lobe Transmission in Multibeam Satellite System

    OpenAIRE

    Gharanjik, Ahmad; Kmieciak, Jarek; Shankar, Bhavani; Ottersten, Björn

    2017-01-01

    In this paper, we study feasibility of coverage extension of a multibeam satellite network by providing low-rate communications to terminals located outside the coverage of main beams. Focusing on the MEO satellite network, and using realistic link budgets from O3b networks, we investigate the performance of both forward and return-links for terminals stationed in the side lobes of the main beams. Particularly, multi-carrier transmission for forward-link and single carrier transmission for re...

  16. Application of communications satellites to educational development. [technology utilization/information systems - bibliographies

    Science.gov (United States)

    Morgan, R. P.

    1975-01-01

    A summary of research is presented. The broad objectives of this interdisciplinary research effort were: (1) to assess the role of satellite communications as a means of improving education in the United States, as well as in less-developed areas of the world; (2) to generate basic knowledge which will aid in making rational decisions about satellite application in the field of education in the years ahead; (3) to devise systems and strategies for improving education; and (4) to educate individuals who will be knowledgeable about aspects of satellite communications policy which transcend any single discipline.

  17. Differential requirement for satellite cells during overload-induced muscle hypertrophy in growing versus mature mice.

    Science.gov (United States)

    Murach, Kevin A; White, Sarah H; Wen, Yuan; Ho, Angel; Dupont-Versteegden, Esther E; McCarthy, John J; Peterson, Charlotte A

    2017-07-10

    Pax7+ satellite cells are required for skeletal muscle fiber growth during post-natal development in mice. Satellite cell-mediated myonuclear accretion also appears to persist into early adulthood. Given the important role of satellite cells during muscle development, we hypothesized that the necessity of satellite cells for adaptation to an imposed hypertrophic stimulus depends on maturational age. Pax7 CreER -R26R DTA mice were treated for 5 days with vehicle (satellite cell-replete, SC+) or tamoxifen (satellite cell-depleted, SC-) at 2 months (young) and 4 months (mature) of age. Following a 2-week washout, mice were subjected to sham surgery or 10 day synergist ablation overload of the plantaris (n = 6-9 per group). The surgical approach minimized regeneration, de novo fiber formation, and fiber splitting while promoting muscle fiber growth. Satellite cell density (Pax7+ cells/fiber), embryonic myosin heavy chain expression (eMyHC), and muscle fiber cross sectional area (CSA) were evaluated via immunohistochemistry. Myonuclei (myonuclei/100 mm) were counted on isolated single muscle fibers. Tamoxifen treatment depleted satellite cells by ≥90% and prevented myonuclear accretion with overload in young and mature mice (p overload. Average muscle fiber CSA increased ~20% in young SC+ (p = 0.07), mature SC+ (p overload (p overload-induced hypertrophy is dependent on maturational age, and global responses to overload differ in young versus mature mice.

  18. A coordinated two-satellite study of energetic electron precipitation events

    International Nuclear Information System (INIS)

    Imhof, W.L.; Nakano, G.H.; Gaines, E.E.; Reagan, J.B.

    1975-01-01

    A new technique for studying the spatial/temporal variations of energetic electron precipitation events is investigated. Data are presented in which precipitating electrons were measured simultaneously on two coordinated polar-orbiting satellites and the bremsstrahlung produced by the electrons precipitating into the atmosphere was observed from one of the satellites. Two electron spectrometers measuring the intensities and energy spectra of electrons of >130 keV were located on the oriented satellite 1971-089A (altitude, approx. =800 km), whereas a single similar spectrometer measuring electrons of >160 keV was located on the spinning low-altitude (approx.750 km) satellite 1972-076B. The X rays of >50 keV were measured with a 50-cm 3 germanium spectrometer placed on the 1972-076B satellite. With the coordinated data a study is made of events in which large fluctuations were observed in the precipitating energetic electron intensities. In the examples presented the satellite X ray data alone demonstrate that the spatially integrated electron influx was constant in time, and when the X ray data are combined with the direct electron measurements from the two satellites, the resulting data suggest that the major features in the flux profiles were primarily spatial in nature. The combination of X ray and electron measurements from two satellites is shown to provide an important method for studying and attempting to resolve spatial and temporal effects

  19. Sustained Satellite Missions for Climate Data Records

    Science.gov (United States)

    Halpern, David

    2012-01-01

    Satellite CDRs possess the accuracy, longevity, and stability for sustained moni toring of critical variables to enhance understanding of the global integrated Earth system and predict future conditions. center dot Satellite CDRs are a critical element of a global climate observing system. center dot Satellite CDRs are a difficult challenge and require high - level managerial commitment, extensive intellectual capital, and adequate funding.

  20. Detecting potential ship objects from satellite pictures

    International Nuclear Information System (INIS)

    Luo, B.; Yang, C.C.; Chang, S.K.; Yang, M.C.K.

    1984-01-01

    Heuristic techniques are presented to detect potential ship objects from satellite pictures. These techniques utilize some noise structures of the pixel gray levels, and certain inherent features of a ship in a satellite picture. The scheme has been implemented and successfully tested on SEASAT satellite pictures. A general approach for database-oriented object detection is also suggested

  1. Computing Thermal Imbalance Forces On Satellites

    Science.gov (United States)

    Vigue, Yvonne; Schutz, Robert E.; Sewell, Granville; Abusali, Pothai A. M.

    1994-01-01

    HEAT.PRO computer program calculates imbalance force caused by heating of surfaces of satellite. Calculates thermal imbalance force and determines its effect on orbit of satellite, especially where shadow cast by Earth Causes periodic changes in thermal environment around satellite. Written in FORTRAN 77.

  2. Experiment In Aeronautical-Mobile/Satellite Communication

    Science.gov (United States)

    Jedrey, Thomas C.; Lay, Norman E.; Dessouky, Khaled

    1992-01-01

    Report describes study of performance of digital mobile/satellite communication terminals of advanced design intended for use in ground stations and airplanes in aeronautical-mobile service. Study was collaboration of NASA, Federal Aviation Administration (FAA), Communications Satellite Corp. (COMSAT), and International Maritime Satellite System (INMARSAT).

  3. Smoothing of Fused Spectral Consistent Satellite Images

    DEFF Research Database (Denmark)

    Sveinsson, Johannes; Aanæs, Henrik; Benediktsson, Jon Atli

    2006-01-01

    on satellite data. Additionally, most conventional methods are loosely connected to the image forming physics of the satellite image, giving these methods an ad hoc feel. Vesteinsson et al. (2005) proposed a method of fusion of satellite images that is based on the properties of imaging physics...

  4. 14 CFR 141.91 - Satellite bases.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Satellite bases. 141.91 Section 141.91... OTHER CERTIFICATED AGENCIES PILOT SCHOOLS Operating Rules § 141.91 Satellite bases. The holder of a... assistant chief instructor is designated for each satellite base, and that assistant chief instructor is...

  5. Interim Service ISDN Satellite (ISIS) network model for advanced satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.; Hager, E. Paul

    1991-01-01

    The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Network Model for Advanced Satellite Designs and Experiments describes a model suitable for discrete event simulations. A top-down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ISDN modeling abstractions are added to permit the determination and performance for the NASA Satellite Communications Research (SCAR) Program.

  6. Korea Earth Observation Satellite Program

    Science.gov (United States)

    Baek, Myung-Jin; Kim, Zeen-Chul

    via Korea Aerospace Research Institute (KARI) as the prime contractor in the area of Korea earth observation satellite program to enhance Korea's space program development capability. In this paper, Korea's on-going and future earth observation satellite programs are introduced: KOMPSAT- 1 (Korea Multi Purpose Satellite-1), KOMPSAT-2 and Communication, Broadcasting and Meteorological Satellite (CBMS) program. KOMPSAT-1 satellite successfully launched in December 1999 with Taurus launch vehicle. Since launch, KOMPSAT-1 is downlinking images of Korea Peninsular every day. Until now, KOMPSAT-1 has been operated more than 2 and half years without any major hardware malfunction for the mission operation. KOMPSAT-1 payload has 6.6m panchromatic spatial resolution at 685 km on-orbit and the spacecraft bus had NASA TOMS-EP (Total Ozone Mapping Spectrometer-Earth Probe) spacecraft bus heritage designed and built by TRW, U.S.A.KOMPSAT-1 program was international co-development program between KARI and TRW funded by Korean Government. be launched in 2004. Main mission objective is to provide geo-information products based on the multi-spectral high resolution sensor called Multi-Spectral Camera (MSC) which will provide 1m panchromatic and 4m multi-spectral high resolution images. ELOP of Israel is the prime contractor of the MSC payload system and KARI is the total system prime contractor including spacecraft bus development and ground segment. KARI also has the contract with Astrium of Europe for the purpose of technical consultation and hardware procurement. Based on the experience throughout KOMPSAT-1 and KOMPSAT-2 space system development, Korea is expecting to establish the infrastructure of developing satellite system. Currently, KOMPSAT-2 program is in the critical design stage. are scheduled to launch in 2008 and in 2014, respectively. The mission of CBMS consists of two areas. One is of space technology test for the communications mission, and the other is of a real

  7. Implementation of Multiple Access Techniques Applicable for Maritime Satellite Communications

    Directory of Open Access Journals (Sweden)

    Stojce Dimov Ilcev

    2013-12-01

    Full Text Available In this paper are introduced fundamentals, characteristics, advantages and disadvantages of Multiple Access (MA employed as transmission techniques in the Maritime Mobile Satellite Communications (MMSC between ships and Coast Earth Station (CES via Geostationary Earth Orbit (GEO or Not-GEO satellite constellations. In fixed satellite communication, as a rule, especially in MMSC many users are active at the same time. The problem of simultaneous communications between many single or multipoint mobile satellite users can be solved by using MA technique, such as Frequency Division Multiple Access (FDMA, Time Division Multiple Access (TDMA, Code Division Multiple Access (CDMA, Space Division Multiple Access (SDMA and Random (Packet Division Multiple Access (RDMA. Since the resources of the systems such as the transmitting power and the bandwidth are limited, it is advisable to use the channels with complete charge and to create a different MA to the channel. This generates a problem of summation and separation of signals in the transmission and reception parts, respectively. Deciding this problem consists in the development of orthogonal channels of transmission in order to divide signals from various users unambiguously on the reception part.

  8. Advanced Solar Cells for Satellite Power Systems

    Science.gov (United States)

    Flood, Dennis J.; Weinberg, Irving

    1994-01-01

    The multiple natures of today's space missions with regard to operational lifetime, orbital environment, cost and size of spacecraft, to name just a few, present such a broad range of performance requirements to be met by the solar array that no single design can suffice to meet them all. The result is a demand for development of specialized solar cell types that help to optimize overall satellite performance within a specified cost range for any given space mission. Historically, space solar array performance has been optimized for a given mission by tailoring the features of silicon solar cells to account for the orbital environment and average operating conditions expected during the mission. It has become necessary to turn to entirely new photovoltaic materials and device designs to meet the requirements of future missions, both in the near and far term. This paper will outline some of the mission drivers and resulting performance requirements that must be met by advanced solar cells, and provide an overview of some of the advanced cell technologies under development to meet them. The discussion will include high efficiency, radiation hard single junction cells; monolithic and mechanically stacked multiple bandgap cells; and thin film cells.

  9. Combined Global Navigation Satellite Systems in the Space Service Volume

    Science.gov (United States)

    Force, Dale A.; Miller, James J.

    2013-01-01

    approximately two thousand grid points evenly spaced and fixed in longitude and latitude, the duration of the longest single-fold outages (intervals when no satellites are available), and the duration of the longest four-fold outages (intervals when fewer than four satellites are available) at several altitudes. Following the original paper, we will use the altitudes of three hundred km (typical LEO satellite, and within the Terrestrial Service Volume), at three thousand km (border between Terrestrial Service Volume and Space Service Volume), at eight thousand km (the border between medium and high orbit service within the Space Service Volume), at fifteen thousand km (just below the GNSS constellations), at twenty five thousand km (just above the GNSS constellations), at thirty six thousand, five hundred km (limit of Space Service Volume definition, geosynchronous altitude), and at seventy thousand km (to show the potential usefulness of GNSS beyond geosynchronous altitude).

  10. UV Spectrophotometry of the Galilean Satellites, Saturnian Satellites & Selected Asteroids

    Science.gov (United States)

    Nelson, Robert M.

    We propose a series of ultraviolet spectral observations of solid surfaces of selected solar system objects, specifically the Galilean satellites of Jupiter, several atmosphereless satellites of Saturn, and the asteroids, 5 Astraea, 18 Melpomene, 532 Herculina, 68 Leto, 31 Euphmsyne, 80 Sappho, 3 Juno, and 39 Laetitia. Historically such spectral observations have allowed for the Identification of spectrally active solid state materials on planetary surfaces. Furthermore, because the rotational properties are known for all the objects proposed for study, this technique will provide a longitude map of such materials on the objects' surfaces. The study of asteroid surface mineralogy is an important method of constraining solar system formation models. The asteroid spectra we have previously acquired with IUE have created unique subdivisions within the existent asteroid types. The new spectra will provide more sophisticated mineralogical characterizations of asteroid surface materials. Our other accomplishments with IUE include mapping of the distribution of condensed S02 on Io, identification of a longitudinal asymmetry on Europa associated with magnetospheric particle bombardment of the surface, and establishing the ultraviolet geometric albedo variation as a function of longitude for all the Galilean satellites. Because Io is the most volcanically active body In the solar system, and short tern variations in selected regions of the Jovian magnetosphere are known to occur, it is important to periodically check for temporal variations in the spectra of the Galilean satellites that may be due to variations n Io tectonic/volcanic activity, or magnetosphere changes. These proposed UV observations are critical to the design and operation of several instruments on Project Galileo, NASA's Jupiter Orbiter and Probe Mission. Spectra of Iapetus, Rhea and Dione have been acquired during the previous year; however, only at orbital locations near elongation. In addition, the dark

  11. Ocean tides for satellite geodesy

    Science.gov (United States)

    Dickman, S. R.

    1990-01-01

    Spherical harmonic tidal solutions have been obtained at the frequencies of the 32 largest luni-solar tides using prior theory of the author. That theory was developed for turbulent, nonglobal, self-gravitating, and loading oceans possessing realistic bathymetry and linearized bottom friction; the oceans satisfy no-flow boundary conditions at coastlines. In this theory the eddy viscosity and bottom drag coefficients are treated as spatially uniform. Comparison of the predicted degree-2 components of the Mf, P1, and M2 tides with those from numerical and satellite-based tide models allows the ocean friction parameters to be estimated at long and short periods. Using the 32 tide solutions, the frequency dependence of tidal admittance is investigated, and the validity of sideband tide models used in satellite orbit analysis is examined. The implications of admittance variability for oceanic resonances are also explored.

  12. Induction studies with satellite data

    DEFF Research Database (Denmark)

    Olsen, Nils

    1999-01-01

    The natural variations of the Earth's magnetic field of periods spanning from milliseconds to decades can be used to infer the conductivity-depth profile of the Earth's interior. Satellites provide a good spatial coverage of magnetic measurements, and forthcoming missions will probably allow...... for observations lasting several years, which helps to reduce the statistical error of the estimated response functions. Two methods are used to study the electrical conductivity of the Earth's mantle in the period range from hours to months. In the first, known as the potential method, a spherical harmonic...... days, this difference probably is not caused purely by differences in mantle conductivity (for which one would expect less difference for the longer periods). Further studies with data from recently launched and future satellites are needed....

  13. Satellite communications network design and analysis

    CERN Document Server

    Jo, Kenneth Y

    2011-01-01

    This authoritative book provides a thorough understanding of the fundamental concepts of satellite communications (SATCOM) network design and performance assessments. You find discussions on a wide class of SATCOM networks using satellites as core components, as well as coverage key applications in the field. This in-depth resource presents a broad range of critical topics, from geosynchronous Earth orbiting (GEO) satellites and direct broadcast satellite systems, to low Earth orbiting (LEO) satellites, radio standards and protocols.This invaluable reference explains the many specific uses of

  14. THERMAL AND VISIBLE SATELLITE IMAGE FUSION USING WAVELET IN REMOTE SENSING AND SATELLITE IMAGE PROCESSING

    Directory of Open Access Journals (Sweden)

    A. H. Ahrari

    2017-09-01

    Full Text Available Multimodal remote sensing approach is based on merging different data in different portions of electromagnetic radiation that improves the accuracy in satellite image processing and interpretations. Remote Sensing Visible and thermal infrared bands independently contain valuable spatial and spectral information. Visible bands make enough information spatially and thermal makes more different radiometric and spectral information than visible. However low spatial resolution is the most important limitation in thermal infrared bands. Using satellite image fusion, it is possible to merge them as a single thermal image that contains high spectral and spatial information at the same time. The aim of this study is a performance assessment of thermal and visible image fusion quantitatively and qualitatively with wavelet transform and different filters. In this research, wavelet algorithm (Haar and different decomposition filters (mean.linear,ma,min and rand for thermal and panchromatic bands of Landast8 Satellite were applied as shortwave and longwave fusion method . Finally, quality assessment has been done with quantitative and qualitative approaches. Quantitative parameters such as Entropy, Standard Deviation, Cross Correlation, Q Factor and Mutual Information were used. For thermal and visible image fusion accuracy assessment, all parameters (quantitative and qualitative must be analysed with respect to each other. Among all relevant statistical factors, correlation has the most meaningful result and similarity to the qualitative assessment. Results showed that mean and linear filters make better fused images against the other filters in Haar algorithm. Linear and mean filters have same performance and there is not any difference between their qualitative and quantitative results.

  15. The Swedish satellite project Viking

    International Nuclear Information System (INIS)

    Hultqvist, B.

    1990-01-01

    The Swedish satellite project Viking is described and related to earlier missions. Some new operational characteristics are discussed, including the real-time data analysis campaigns that were an important part of the project. Some areas of important scientific impact of the project are also described. Viking was specially designed and equipped for investigation of plasma physical acceleration and other processes in the transition region between hot and cold plasma on auroral latitude magnetic field lines

  16. Hybrid Maritime Satellite Communication Antenna

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst

    Hybrid antennas for a maritime satellite communication terminal with simultaneous operation at L- and Ka-band have been investigated. The frequency bands of interest are 1; 525:0 1; 660:5 MHz (RX+TX, RHCP), 19:7 20:2 (RX, LHCP) and 29:5 30:0 GHz (TX, RHCP), which are all part of the Inmarsat BGAN...

  17. SDR Implementation for Satellite Communication

    OpenAIRE

    Jakobsson, Carin; Sjödin, Olof

    2017-01-01

    SDR (Software Defined Radio) is a radio communicationsystem that has been of great interest and developmentover the last 20 years. It decreases communication costs significantlyas it replaces expensive analogue system components withcheap and flexible digital ones. In this article we describe anSDR implementation for communication with the SEAM (SmallExplorer for Advances Missions) satellite, a CubeSat satellitethat will perform high quality magnetic measurements in theEarth orbit. The projec...

  18. Collage of Saturn's smaller satellites

    Science.gov (United States)

    1981-01-01

    This family portrait shows the smaller satellites of Saturn as viewed by Voyager 2 during its swing through the Saturnian system. The following chart corresponds to this composite photograph (distance from the planet increases from left to right) and lists names, standard numerical designations and approximate dimensions (radii where indicated) in kilometers: 1980S26Outer F-ringshepherd120 X 100 1980S1Leadingco-orbital220 X 160 1980S25TrailingTethys trojanradii: 25 1980S28Outer Ashepherdradii: 20 1980S27Inner F-ringco-orbital145 X 70 1980S3TrailingTethys trojan140 X 100 1980S13LeadingTethys trojanradii: 30 1980S6LeadingDione trojanradii: 30 These images have been scaled to show the satellites in true relative sizes. This set of small objects ranges in size from small asteroidal scales to nearly the size of Saturn's moon Mimas. They are probably fragments of somewhat larger bodies broken up during the bombardment period that followed accretion of the Saturnian system. Scientists believe they may be mostly icy bodies with a mixture of meteorite rock. They are somewhat less reflective than the larger satellites, suggesting that thermal evolution of the larger moons 'cleaned up' their icy surfaces. The Voyager project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.

  19. Satellite-based laser windsounder

    International Nuclear Information System (INIS)

    Schultz, J.F.; Czuchlewski, S.J.; Quick, C.R.

    1997-01-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project''s primary objective is to determine the technical feasibility of using satellite-based laser wind sensing systems for detailed study of winds, aerosols, and particulates around and downstream of suspected proliferation facilities. Extensive interactions with the relevant operational organization resulted in enthusiastic support and useful guidance with respect to measurement requirements and priorities. Four candidate wind sensing techniques were evaluated, and the incoherent Doppler technique was selected. A small satellite concept design study was completed to identify the technical issues inherent in a proof-of-concept small satellite mission. Use of a Mach-Zehnder interferometer instead of a Fabry-Perot would significantly simplify the optical train and could reduce weight, and possibly power, requirements with no loss of performance. A breadboard Mach-Zehnder interferometer-based system has been built to verify these predictions. Detailed plans were made for resolving other issues through construction and testing of a ground-based lidar system in collaboration with the University of Wisconsin, and through numerical lidar wind data assimilation studies

  20. Phillips Laboratory small satellite initiatives

    Science.gov (United States)

    Lutey, Mark K.; Imler, Thomas A.; Davis, Robert J.

    1993-09-01

    The Phillips Laboratory Space Experiments Directorate in conjunction with the Air Force Space Test Program (AF STP), Defense Advanced Research and Projects Agency (DARPA) and Strategic Defense Initiative Organization (SDIO), are managing five small satellite program initiatives: Lightweight Exo-Atmospheric Projectile (LEAP) sponsored by SDIO, Miniature Sensor Technology Integration (MSTI) sponsored by SDIO, Technology for Autonomous Operational Survivability (TAOS) sponsored by Phillips Laboratory, TechSat sponsored by SDIO, and the Advanced Technology Standard Satellite Bus (ATSSB) sponsored by DARPA. Each of these spacecraft fulfills a unique set of program requirements. These program requirements range from a short-lived `one-of-a-kind' mission to the robust multi- mission role. Because of these diverging requirements, each program is driven to use a different design philosophy. But regardless of their design, there is the underlying fact that small satellites do not always equate to small missions. These spacecraft with their use of or ability to insert new technologies provide more capabilities and services for their respective payloads which allows the expansion of their mission role. These varying program efforts culminate in an ATSSB spacecraft bus approach that will support moderate size payloads, up to 500 pounds, in a large set of orbits while satisfying the `cheaper, faster, better' method of doing business. This technical paper provides an overview of each of the five spacecraft, focusing on the objectives, payoffs, technologies demonstrated, and program status.

  1. Satellite Attitude Control System Simulator

    Directory of Open Access Journals (Sweden)

    G.T. Conti

    2008-01-01

    Full Text Available Future space missions will involve satellites with great autonomy and stringent pointing precision, requiring of the Attitude Control Systems (ACS with better performance than before, which is function of the control algorithms implemented on board computers. The difficulties for developing experimental ACS test is to obtain zero gravity and torque free conditions similar to the SCA operate in space. However, prototypes for control algorithms experimental verification are fundamental for space mission success. This paper presents the parameters estimation such as inertia matrix and position of mass centre of a Satellite Attitude Control System Simulator (SACSS, using algorithms based on least square regression and least square recursive methods. Simulations have shown that both methods have estimated the system parameters with small error. However, the least square recursive methods have performance more adequate for the SACSS objectives. The SACSS platform model will be used to do experimental verification of fundamental aspects of the satellite attitude dynamics and design of different attitude control algorithm.

  2. Antennas for mobile satellite communications

    Science.gov (United States)

    Huang, John

    1991-12-01

    A NASA sponsored program, called the Mobile Satellite (MSAT) system, has prompted the development of several innovative antennas at L-band frequencies. In the space segment of the MSAT system, an efficient, light weight, circularly polarized microstrip array that uses linearly polarized elements was developed as a multiple beam reflector feed system. In the ground segment, a low-cost, low-profile, and very efficient microstrip Yagi array was developed as a medium-gain mechanically steered vehicle antenna. Circularly shaped microstrip patches excited at higher-order modes were also developed as low-gain vehicle antennas. A more recent effort called for the development of a 20/30 GHz mobile terminal antenna for future-generation mobile satellite communications. To combat the high insertion loss encountered at 20/30 GHz, series-fed Monolithic Microwave Integrated Circuit (MMIC) microstrip array antennas are currently being developed. These MMIC arrays may lead to the development of several small but high-gain Ka-band antennas for the Personal Access Satellite Service planned for the 2000s.

  3. The Giant Planet Satellite Exospheres

    Science.gov (United States)

    McGrath, Melissa A.

    2014-01-01

    Exospheres are relatively common in the outer solar system among the moons of the gas giant planets. They span the range from very tenuous, surface-bounded exospheres (e.g., Rhea, Dione) to quite robust exospheres with exobase above the surface (e.g., lo, Triton), and include many intermediate cases (e.g., Europa, Ganymede, Enceladus). The exospheres of these moons exhibit an interesting variety of sources, from surface sputtering, to frost sublimation, to active plumes, and also well illustrate another common characteristic of the outer planet satellite exospheres, namely, that the primary species often exists both as a gas in atmosphere, and a condensate (frost or ice) on the surface. As described by Yelle et al. (1995) for Triton, "The interchange of matter between gas and solid phases on these bodies has profound effects on the physical state of the surface and the structure of the atmosphere." A brief overview of the exospheres of the outer planet satellites will be presented, including an inter-comparison of these satellites exospheres with each other, and with the exospheres of the Moon and Mercury.

  4. Weather Satellite Pictures and How to Obtain Them.

    Science.gov (United States)

    Petit, Noel J.; Johnson, Philip

    1982-01-01

    An introduction to satellite meteorology is presented to promote use of live weather satellite photographs in the classroom. Topics addressed include weather satellites, how they work, earth emissions, satellite photography, satellite image analysis, obtaining satellite pictures, and future considerations. Includes sources for materials to…

  5. Satellite cells in human skeletal muscle plasticity.

    Science.gov (United States)

    Snijders, Tim; Nederveen, Joshua P; McKay, Bryon R; Joanisse, Sophie; Verdijk, Lex B; van Loon, Luc J C; Parise, Gianni

    2015-01-01

    Skeletal muscle satellite cells are considered to play a crucial role in muscle fiber maintenance, repair and remodeling. Our knowledge of the role of satellite cells in muscle fiber adaptation has traditionally relied on in vitro cell and in vivo animal models. Over the past decade, a genuine effort has been made to translate these results to humans under physiological conditions. Findings from in vivo human studies suggest that satellite cells play a key role in skeletal muscle fiber repair/remodeling in response to exercise. Mounting evidence indicates that aging has a profound impact on the regulation of satellite cells in human skeletal muscle. Yet, the precise role of satellite cells in the development of muscle fiber atrophy with age remains unresolved. This review seeks to integrate recent results from in vivo human studies on satellite cell function in muscle fiber repair/remodeling in the wider context of satellite cell biology whose literature is largely based on animal and cell models.

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

    Science.gov (United States)

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

    2011-09-01

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

  7. single crystals

    Indian Academy of Sciences (India)

    2018-05-18

    May 18, 2018 ... Abstract. 4-Nitrobenzoic acid (4-NBA) single crystals were studied for their linear and nonlinear optical ... studies on the proper growth, linear and nonlinear optical ..... between the optic axes and optic sign of the biaxial crystal.

  8. Prediction of GNSS satellite clocks

    International Nuclear Information System (INIS)

    Broederbauer, V.

    2010-01-01

    This thesis deals with the characterisation and prediction of GNSS-satellite-clocks. A prerequisite to develop powerful algorithms for the prediction of clock-corrections is the thorough study of the behaviour of the different clock-types of the satellites. In this context the predicted part of the IGU-clock-corrections provided by the Analysis Centers (ACs) of the IGS was compared to the IGS-Rapid-clock solutions to determine reasonable estimates of the quality of already existing well performing predictions. For the shortest investigated interval (three hours) all ACs obtain almost the same accuracy of 0,1 to 0,4 ns. For longer intervals the individual predictions results start to diverge. Thus, for a 12-hours- interval the differences range from nearly 10 ns (GFZ, CODE) until up to some 'tens of ns'. Based on the estimated clock corrections provided via the IGS Rapid products a simple quadratic polynomial turns out to be sufficient to describe the time series of Rubidium-clocks. On the other hand Cesium-clocks show a periodical behaviour (revolution period) with an amplitude of up to 6 ns. A clear correlation between these amplitudes and the Sun elevation angle above the orbital planes can be demonstrated. The variability of the amplitudes is supposed to be caused by temperature-variations affecting the oscillator. To account for this periodical behaviour a quadratic polynomial with an additional sinus-term was finally chosen as prediction model both for the Cesium as well as for the Rubidium clocks. The three polynomial-parameters as well as amplitude and phase shift of the periodic term are estimated within a least-square-adjustment by means of program GNSS-VC/static. Input-data are time series of the observed part of the IGU clock corrections. With the estimated parameters clock-corrections are predicted for various durations. The mean error of the prediction of Rubidium-clock-corrections for an interval of six hours reaches up to 1,5 ns. For the 12-hours

  9. Contrast in low-cost operational concepts for orbiting satellites

    Science.gov (United States)

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

    2002-12-01

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

  10. Observing System Simulations for Small Satellite Formations Estimating Bidirectional Reflectance

    Science.gov (United States)

    Nag, Sreeja; Gatebe, Charles K.; de Weck, Olivier

    2015-01-01

    The bidirectional reflectance distribution function (BRDF) gives the reflectance of a target as a function of illumination geometry and viewing geometry, hence carries information about the anisotropy of the surface. BRDF is needed in remote sensing for the correction of view and illumination angle effects (for example in image standardization and mosaicing), for deriving albedo, for land cover classification, for cloud detection, for atmospheric correction, and other applications. However, current spaceborne instruments provide sparse angular sampling of BRDF and airborne instruments are limited in the spatial and temporal coverage. To fill the gaps in angular coverage within spatial, spectral and temporal requirements, we propose a new measurement technique: Use of small satellites in formation flight, each satellite with a VNIR (visible and near infrared) imaging spectrometer, to make multi-spectral, near-simultaneous measurements of every ground spot in the swath at multiple angles. This paper describes an observing system simulation experiment (OSSE) to evaluate the proposed concept and select the optimal formation architecture that minimizes BRDF uncertainties. The variables of the OSSE are identified; number of satellites, measurement spread in the view zenith and relative azimuth with respect to solar plane, solar zenith angle, BRDF models and wavelength of reflection. Analyzing the sensitivity of BRDF estimation errors to the variables allow simplification of the OSSE, to enable its use to rapidly evaluate formation architectures. A 6-satellite formation is shown to produce lower BRDF estimation errors, purely in terms of angular sampling as evaluated by the OSSE, than a single spacecraft with 9 forward-aft sensors. We demonstrate the ability to use OSSEs to design small satellite formations as complements to flagship mission data. The formations can fill angular sampling gaps and enable better BRDF products than currently possible.

  11. A New Satellite System for Measuring BRDF from Space

    Science.gov (United States)

    Wiscombe, W.; Kaufman, Y.; Herman, J.

    1999-01-01

    Formation flying of satellites is at the beginning of an explosive growth curve. Spacecraft buses are shrinking to the point where we will soon be able to launch 10 micro-satellites or 100 nano-satellites on a single launch vehicle. Simultaneously, spectrometers are just beginning to be flown in space by both the U.S. and Europe. On-board programmable band aggregation will soon allow exactly the spectral bands desired to be returned to Earth. Further efforts are being devoted to radically shrink spectrometers both in size and weight. And GPS positioning and attitude determination, plus new technologies for attitude control, will allow fleets of satellites to all point at the same Earth target. All these advances, in combination, make possible for the first time the proper measurement of Bidirectional Reflectance Distribution (BRDF) form space. Previously space BDRF's were mere composites, built up over time by viewing different types of scenes at different times, then creating catalogs of BDRF functions whose use relied upon correct "scene identification" --the weak link. Formation-flying micro-satellites, carrying programmable spectrometers and precision-pointing at the same Earth target, can measure the full BDRF simultaneously, in real time. This talk will review these technological advances and discuss an actual proposed concept, based on these advances, to measure Earth-target BDRF's (clouds as well as surface) across the full solar spectrum in the 2010 timeframe. This concept is part of a larger concept called Leonardo for properly measuring the radiative forcing of Earth for climate purposes; lack of knowing of BDRF and of diurnal cycle are at present the two limiting factors preventing improved estimates of this forcing.

  12. Observing system simulations for small satellite formations estimating bidirectional reflectance

    Science.gov (United States)

    Nag, Sreeja; Gatebe, Charles K.; Weck, Olivier de

    2015-12-01

    The bidirectional reflectance distribution function (BRDF) gives the reflectance of a target as a function of illumination geometry and viewing geometry, hence carries information about the anisotropy of the surface. BRDF is needed in remote sensing for the correction of view and illumination angle effects (for example in image standardization and mosaicing), for deriving albedo, for land cover classification, for cloud detection, for atmospheric correction, and other applications. However, current spaceborne instruments provide sparse angular sampling of BRDF and airborne instruments are limited in the spatial and temporal coverage. To fill the gaps in angular coverage within spatial, spectral and temporal requirements, we propose a new measurement technique: use of small satellites in formation flight, each satellite with a VNIR (visible and near infrared) imaging spectrometer, to make multi-spectral, near-simultaneous measurements of every ground spot in the swath at multiple angles. This paper describes an observing system simulation experiment (OSSE) to evaluate the proposed concept and select the optimal formation architecture that minimizes BRDF uncertainties. The variables of the OSSE are identified; number of satellites, measurement spread in the view zenith and relative azimuth with respect to solar plane, solar zenith angle, BRDF models and wavelength of reflection. Analyzing the sensitivity of BRDF estimation errors to the variables allow simplification of the OSSE, to enable its use to rapidly evaluate formation architectures. A 6-satellite formation is shown to produce lower BRDF estimation errors, purely in terms of angular sampling as evaluated by the OSSE, than a single spacecraft with 9 forward-aft sensors. We demonstrate the ability to use OSSEs to design small satellite formations as complements to flagship mission data. The formations can fill angular sampling gaps and enable better BRDF products than currently possible.

  13. Stability of a dual-spin satellite with two dampers

    Science.gov (United States)

    Alfriend, K. T.; Hubert, C. H.

    1974-01-01

    The rotational stability of a dual-spin satellite consisting of a main body and a symmetric rotor, both spinning about a common axis, is investigated. The main body is equipped with a spring-mass damper, while a partially filled viscous ring damper is mounted on the rapidly spinning rotor. The effect of fluid motion on the rotational stability of the satellite is calculated, considering the fluid as a single particle moving in a tube with viscous damping. Time constants are obtained by solving approximate equations of motion for the nutation-synchronous and the spin-synchronous modes, and the results are found to agree well with the numerical integrations of the exact equations. A limit cycle may exist for some configurations; the nutation angle tends to increase in such cases.

  14. Calculation of charge-state ratios for satellite Tor I

    Science.gov (United States)

    Summers, D.; Siscoe, G. L.

    1985-01-01

    The diffusion of ions in a satellite plasma torus is presently modeled in terms of a one-dimensional random walk in which the particle source is at 0, the particle sink is at an N value that is an integer greater than 2, and the scale size of the diffusion cell is unity. The probability distribution function of the number of steps to exit for an ion is obtained and used in a model which incorporates ionization by electron impact to derive steady state expressions for the ratio of doubly to singly ionized ions, as well as the total number of ions in the torus. The results thus obtained are applied to the torus of the Jovian satellite Io, in order to predict mean residence times for sulfur and oxygen ions.

  15. Overview of the Anik C satellites and services

    Science.gov (United States)

    Smart, F. H.

    An overview of the important technical characteristics of the Anik C series of Canadian communications satellites is presented. The system was launched as part of the Telesat Communications payload of the Space Shuttle in 1982. Among the services the system will in the near future provide are: a 27 MHz channel bandwidth television service for pay-TV distribution in Canada; two TV channels for hockey broadcasts and a transportable TV system; a heavy-voice route telephone service for five major Canadian cities; and a telephone system for business voice and data communications. Services anticipated for Anik-C satellites later in the decade include a Single Channel Per Carrier (SCPC) voice and data communications system for British Columbia and the Maritime Provinces, and a direct-to-home broadcast service to be sold to television markets in the United States.

  16. Satellite-Based Sunshine Duration for Europe

    Directory of Open Access Journals (Sweden)

    Bodo Ahrens

    2013-06-01

    Full Text Available In this study, two different methods were applied to derive daily and monthly sunshine duration based on high-resolution satellite products provided by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT Satellite Application Facility on Climate Monitoring using data from Meteosat Second Generation (MSG SEVIRI (Spinning Enhanced Visible and Infrared Imager. The satellite products were either hourly cloud type or hourly surface incoming direct radiation. The satellite sunshine duration estimates were not found to be significantly different using the native 15-minute temporal resolution of SEVIRI. The satellite-based sunshine duration products give additional spatial information over the European continent compared with equivalent in situ-based products. An evaluation of the satellite sunshine duration by product intercomparison and against station measurements was carried out to determine their accuracy. The satellite data were found to be within ±1 h/day compared to high-quality Baseline Surface Radiation Network or surface synoptic observations (SYNOP station measurements. The satellite-based products differ more over the oceans than over land, mainly because of the treatment of fractional clouds in the cloud type-based sunshine duration product. This paper presents the methods used to derive the satellite sunshine duration products and the performance of the different retrievals. The main benefits and disadvantages compared to station-based products are also discussed.

  17. Activities of Canadian Satellite Communications, Inc.

    Science.gov (United States)

    1992-12-01

    Canadian Satellite Communications (Cancom) has as its core business the provision of television and radio signals to cable systems in Canada, with the objective of making affordable broadcast signals available to remote and/or small communities. Cancom also provides direct-to-home services to backyard receiving dishes, as well as satellite digital data business communications services, satellite business television, and satellite network services. Its business communication services range from satellite links for big-city businesses with small branch operations located far from major centers, to a mobile messaging and tracking system for the trucking industry. Revenues in 1992 totalled $48,212,000 and net income was just over $7 million. Cancom bought 10 percent interest in Leosat Corp. of Washington, DC, who are seeking approval to operate a position locator network from low-orbit satellites. Cancom has also become a partner in SovCan Star Satellite Communications Inc., which will build an international satellite system in partnership with Russia. The first satellite in this east-west business network will be placed in a Russian orbital slot over the Atlantic by 1996, and a second satellite will follow for the Pacific region. This annual report of Cancom's activities for 1992 includes financial statements and a six year financial review.

  18. An Extended ADOP for Performance Evaluation of Single-Frequency Single-Epoch Positioning by BDS/GPS in Asia-Pacific Region

    Directory of Open Access Journals (Sweden)

    Xin Liu

    2017-09-01

    Full Text Available Single-Frequency Single-Epoch (SFSE high-precision positioning has always been the hot spot of Global Navigation Satellite System (GNSS, and ambiguity dilution of precision (ADOP is a well-known scalar measure for success rate of ambiguity resolution. Traditional ADOP expression is complicated, thus the SFSE extended ADOP (E-ADOP, with the newly defined Summation-Multiplication Ratio of Weight (SMRW and two theorems for short baseline, was developed. This simplifies the ADOP expression; gives a clearer insight into the influences of SMRW and number of satellites on E-ADOP; and makes theoretical analysis of E-ADOP more convenient than that of ADOP, and through that the E-ADOP value can be predicted more accurately than through the ADOP expression for ADOP value. E-ADOP reveals that number of satellites and SMRW or high-elevation satellite are important for ADOP and, through E-ADOP, we studied which factor is dominant to control ADOP in different conditions and make ADOP different between BeiDou Navigation Satellite System (BDS, Global Positioning System (GPS, and BDS/GPS. Based on experimental results of SFSE positioning with different baselines, some conclusions are made: (1 ADOP decreases when new satellites are added mainly because the number of satellites becomes larger; (2 when the number of satellites is constant, ADOP is mainly affected by SMRW; (3 in contrast to systems where the satellites with low-elevation are the majority or where low- and high-elevation satellites are equally distributed, in systems where the high-elevation satellites are the majority, the SMRW mainly makes ADOP smaller, even if there are fewer satellites than in the two previous cases, and the difference in numbers of satellites can be expanded as the proportion of high-elevation satellites becomes larger; and (4 ADOP of BDS is smaller than ADOP of GPS mainly because of its SMRW.

  19. An alternative ionospheric correction model for global navigation satellite systems

    Science.gov (United States)

    Hoque, M. M.; Jakowski, N.

    2015-04-01

    The ionosphere is recognized as a major error source for single-frequency operations of global navigation satellite systems (GNSS). To enhance single-frequency operations the global positioning system (GPS) uses an ionospheric correction algorithm (ICA) driven by 8 coefficients broadcasted in the navigation message every 24 h. Similarly, the global navigation satellite system Galileo uses the electron density NeQuick model for ionospheric correction. The Galileo satellite vehicles (SVs) transmit 3 ionospheric correction coefficients as driver parameters of the NeQuick model. In the present work, we propose an alternative ionospheric correction algorithm called Neustrelitz TEC broadcast model NTCM-BC that is also applicable for global satellite navigation systems. Like the GPS ICA or Galileo NeQuick, the NTCM-BC can be optimized on a daily basis by utilizing GNSS data obtained at the previous day at monitor stations. To drive the NTCM-BC, 9 ionospheric correction coefficients need to be uploaded to the SVs for broadcasting in the navigation message. Our investigation using GPS data of about 200 worldwide ground stations shows that the 24-h-ahead prediction performance of the NTCM-BC is better than the GPS ICA and comparable to the Galileo NeQuick model. We have found that the 95 percentiles of the prediction error are about 16.1, 16.1 and 13.4 TECU for the GPS ICA, Galileo NeQuick and NTCM-BC, respectively, during a selected quiet ionospheric period, whereas the corresponding numbers are found about 40.5, 28.2 and 26.5 TECU during a selected geomagnetic perturbed period. However, in terms of complexity the NTCM-BC is easier to handle than the Galileo NeQuick and in this respect comparable to the GPS ICA.

  20. Single event upsets correlated with environment

    International Nuclear Information System (INIS)

    Vampola, A.L.; Albin, F.; Lauriente, M.; Wilkinson, D.C.; Allen, J.

    1994-01-01

    Single Event Upset rates on satellites in different Earth orbits are correlated with solar protons and geomagnetic activity and also with the NASA AP8 proton model to extract information about satellite anomalies caused by the space environment. An extensive discussion of the SEU data base from the TOMS solid state recorder and an algorithm for correcting spontaneous upsets in it are included as an Appendix. SAMPEX and TOMS, which have the same memory chips, have similar normalized responses in the South Atlantic Anomaly. SEU rates due to solar protons over the polar caps are within expectations. No geomagnetic activity effects can be discerned in the SEU rates

  1. German telecommunications satellite (Deutscher fernmelde satellit) (DFS-1 and -2)

    Science.gov (United States)

    Hiendlmeier, G.; Schmeller, H.

    1991-01-01

    The German Telecommunications Satellite (DFS) Program is to provide telecommunications service for high data rate transmission of text and video data to the Federal Republic of Germany within the 11-14 GHz and 20-30 GHz bands. The space segment of this program is composed of three satellites, DFS-1, DFS-2, and DFS-3, which will be located at 23.5 degrees E longitude of the geostationary orbit. The DFS will be launched from the Center Spatial Guyanis in French Giana on an Ariane launch vehicle. The mission follows the typical injection sequence: parking orbit, transfer orbit, and earth orbit. Attitude maneuvers will be performed to orient the spacecraft prior to Apogee Kick Motor (AKM) firing. After AKM firing, drift phase orbital and attitude maneuvers will be performed to place the spacecraft in its final geostationary position. The Deep Space Network (DSN) will support the transfer and drift orbit mission phases. Information is presented in tabular form for the following areas: DSN support, compatibility testing, frequency assignments, telemetry, command, and tracking support responsibilities.

  2. Results of the Ongoing Monitoring of the Position of a Geostationary Telecommunication Satellite by the Method of Spatially Separated Basis Receiving of Digital Satellite Television Signals

    Science.gov (United States)

    Bushuev, F.; Kaliuzhnyi, M.; Sybiryakova, Y.; Shulga, O.; Moskalenko, S.; Balagura, O.; Kulishenko, V.

    2016-10-01

    The results of the ongoing monitoring of the position of geostationary telecommunication satellite Eutelsat-13B (13° East) are presented in the article. The results were obtained using a radio engineering complex (RC) of four stations receiving digital satellite television and a data processing centre. The stations are located in Kyiv, Mukachevo, Kharkiv and Mykolaiv. The equipment of each station allows synchronous recording (by the GPS) of fragments of DVB-S signal from the quadrature detector output of the satellite television receiver. Samples of the complex signal are archived and sent to the data processing center through the Internet. Here three linearly independent slant range differences (Δr) for three pairs of the stations are determined as a result of correlation processing of received signals. Every second measured values of Δr are used to calculate Cartesian coordinates (XYZ) of the satellite in the coordinate system WGS84 by multilateration method. The time series of Δr, X, Y and Z obtained during continuous observations from March to May 2015 are presented in the article. Single-measurement errors of Δr, X, Y and Z are equal to 2.6 m, 3540 m, 705 m and 455 m, respectively. The complex is compared with known analogues. Ways of reduction of measurement errors of satellite coordinates are considered. The radio engineering complex could be considered a prototype of a system of independent ongoing monitoring of the position of geostationary telecommunication satellites.

  3. Characterization of non-coding DNA satellites associated with sweepoviruses (genus Begomovirus, Geminiviridae - definition of a distinct class of begomovirus-associated satellites

    Directory of Open Access Journals (Sweden)

    Gloria eLozano

    2016-02-01

    Full Text Available Begomoviruses (family Geminiviridae are whitefly-transmitted, plant-infecting single-stranded DNA viruses that cause crop losses throughout the warmer parts of the World. Sweepoviruses are a phylogenetically distinct group of begomoviruses that infect plants of the family Convolvulaceae, including sweet potato (Ipomoea batatas. Two classes of subviral molecules are often associated with begomoviruses, particularly in the Old World; the betasatellites and the alphasatellites. An analysis of sweet potato and Ipomoea indica samples from Spain and Merremia dissecta samples from Venezuela identified small non-coding subviral molecules in association with several distinct sweepoviruses. The sequences of 18 clones were obtained and found to be structurally similar to tomato leaf curl virus–satellite (ToLCV-sat, the first DNA satellite identified in association with a begomovirus, with a region with significant sequence identity to the conserved region of betasatellites, an A-rich sequence, a predicted stem-loop structure containing the nonanucleotide TAATATTAC, and a second predicted stem-loop. These sweepovirus-associated satellites join an increasing number of ToLCV-sat-like non-coding satellites identified recently. Although sharing some features with betasatellites, evidence is provided to suggest that the ToLCV-sat-like satellites are distinct from betasatellites and should be considered a separate class of satellites, for which the collective name deltasatellites is proposed.

  4. Tracking System : Suaineadh satellite experiment

    OpenAIRE

    Brengesjö, Carl; Selin, Martine

    2011-01-01

    The purpose of this bachelor thesis is to present a tracking system for the Suaineadh satellite experiment. The experiment is a part of the REXUS (Rocket EXperiments for University Students) program and the objective is to deploy a foldable web in space. The assignment of this thesis is to develop a tracking system to find the parts from the Suaineadh experiment that will land on Earth. It is important to find the parts and recover all the data that the experiment performed during the travel ...

  5. An introduction to optimal satellite range scheduling

    CERN Document Server

    Vázquez Álvarez, Antonio José

    2015-01-01

    The satellite range scheduling (SRS) problem, an important operations research problem in the aerospace industry consisting of allocating tasks among satellites and Earth-bound objects, is examined in this book. SRS principles and solutions are applicable to many areas, including: Satellite communications, where tasks are communication intervals between sets of satellites and ground stations Earth observation, where tasks are observations of spots on the Earth by satellites Sensor scheduling, where tasks are observations of satellites by sensors on the Earth. This self-contained monograph begins with a structured compendium of the problem and moves on to explain the optimal approach to the solution, which includes aspects from graph theory, set theory, game theory and belief networks. This book is accessible to students, professionals and researchers in a variety of fields, including: operations research, optimization, scheduling theory, dynamic programming and game theory. Taking account of the distributed, ...

  6. Study of chaos in chaotic satellite systems

    Science.gov (United States)

    Khan, Ayub; Kumar, Sanjay

    2018-01-01

    In this paper, we study the qualitative behaviour of satellite systems using bifurcation diagrams, Poincaré section, Lyapunov exponents, dissipation, equilibrium points, Kaplan-Yorke dimension etc. Bifurcation diagrams with respect to the known parameters of satellite systems are analysed. Poincaré sections with different sowing axes of the satellite are drawn. Eigenvalues of Jacobian matrices for the satellite system at different equilibrium points are calculated to justify the unstable regions. Lyapunov exponents are estimated. From these studies, chaos in satellite system has been established. Solution of equations of motion of the satellite system are drawn in the form of three-dimensional, two-dimensional and time series phase portraits. Phase portraits and time series display the chaotic nature of the considered system.

  7. Kagawa Satellite “STARS” in Shikoku

    Science.gov (United States)

    Nohmi, Masahiro; Yamamoto, Takeshi; Andatsu, Akira; Takagi, Yohei; Nishikawa, Yusuke; Kaneko, Takashi; Kunitom, Daisuke

    The Space Tethered Autonomous Robotic Satellite (STARS) is being developed in Kagawa University, and it will be launched by the H-IIA rocket by Japan Aerospace Exploration Agency (JAXA) in summer 2008. STARS is the first satellite developed in Shikoku, and its specific characteristics are: (i) mother and daughter satellites, which have basic satellite system respectively, and those are launched at the same time; (ii) large space system more than 5m by extending tether; (iii) robotic system, the daughter satellite controls its arm link and the mother satellite controls tether extension. Development of STARS in Kagawa University demonstrates space technology in local community, which has been considered to be a national project. Also, it promotes popularization, enlightenment, and understanding of space technology in local area of the Kagawa prefecture and around it.

  8. Bringing satellite winds to hub-height

    DEFF Research Database (Denmark)

    Badger, Merete; Pena Diaz, Alfredo; Bredesen, Rolv Erlend

    2012-01-01

    Satellite observations of the ocean surface can provide detailed information about the spatial wind variability over large areas. This is very valuable for the mapping of wind resources offshore where other measurements are costly and sparse. Satellite sensors operating at microwave frequencies...... measure the amount of radar backscatter from the sea surface, which is a function of the instant wind speed, wind direction, and satellite viewing geometry. A major limitation related to wind retrievals from satellite observations is that existing empirical model functions relate the radar backscatter...... to wind speed at the height 10 m only. The extrapolation of satellite wind fields to higher heights, which are more relevant for wind energy, remains a challenge which cannot be addressed by means of satellite data alone. As part of the EU-NORSEWInD project (2008-12), a hybrid method has been developed...

  9. The 2010 Eyja eruption evolution by using IR satellite sensors measurements: retrieval comparison and insights into explosive volcanic processes

    Science.gov (United States)

    Piscini, A.; Corradini, S.; Merucci, L.; Scollo, S.

    2010-12-01

    The 2010 April-May Eyja eruption caused an unprecedented disruption to economic, political and cultural activities in Europe and across the world. Because of the harming effects of fine ash particles on aircrafts, many European airports were in fact closed causing millions of passengers to be stranded, and with a worldwide airline industry loss estimated of about 2.5 billion Euros. Both security and economical issues require robust and affordable volcanic cloud retrievals that may be really improved through the intercomparison among different remote sensing instruments. In this work the Thermal InfraRed (TIR) measurements of different polar and geostationary satellites instruments as the Moderate Resolution Imaging Spectroradiometer (MODIS), the Advanced Very High Resolution Radiometer (AVHRR) and the Spin Enhanced Visible and Infrared Imager (SEVIRI), have been used to retrieve the volcanic ash and SO2 in the entire eruption period over Iceland. The ash retrievals (mass, AOD and effective radius) have been carried out by means of the split window BTD technique using the channels centered around 11 and 12 micron. The least square fit procedure is used for the SO2 retrieval by using the 7.3 and 8.7 micron channels. The simulated TOA radiance Look-Up Table (LUT) needed for both the ash and SO2 column abundance retrievals have been computed using the MODTRAN 4 Radiative Transfer Model. Further, the volcanic plume column altitude and ash density have been computed and compared, when available, with ground observations. The results coming from the retrieval of different IR sensors show a good agreement over the entire eruption period. The column height, the volcanic ash and the SO2 emission trend confirm the indentified different phases occurred during the Eyja eruption. We remark that the retrieved volcanic plume evolution can give important insights into eruptive dynamics during long-lived explosive activity.

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

    Science.gov (United States)

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

    2013-12-01

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

  11. History of Satellite Orbit Determination at NSWCDD

    Science.gov (United States)

    2018-01-31

    meeting of the Satellite Division of ION, Palm Springs, CA., 12–15 Sep 1995. Hughey, Raymond H., Jr., “ History of Mathematics and Computing Technology ...TR-17/229 HISTORY OF SATELLITE ORBIT DETERMINATION AT NSWCDD BY EVERETT R. SWIFT WARFARE SYSTEMS ENGINEERING AND INTEGRATION...AND SUBTITLE History of Satellite Orbit Determination at NSWCDD 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

  12. Satellite Communication and Long Distance Education

    OpenAIRE

    Hafied Cangara

    2016-01-01

    Since Indonesia introduced communication satellite for telecommunication network, the satellite has brought a number of advantages for national development in various areas, such as telephone network, mass media development, business, education, politics, security and national defence as well as regional and International cooperation. In education, satellite communication could be used for long-distance learning as implemented by 13 state universities in eastern parts of Indonesia. It is also...

  13. Estimating Rain Attenuation In Satellite Communication Links

    Science.gov (United States)

    Manning, R. M.

    1991-01-01

    Attenuation computed with help of statistical model and meteorological data. NASA Lewis Research Center Satellite Link Attenuation Model (SLAM) program QuickBASIC computer program evaluating static and dynamic statistical assessment of impact of rain attenuation on communication link established between Earth terminal and geosynchronous satellite. Application in specification, design, and assessment of satellite communication links for any terminal location in continental United States. Written in Microsoft QuickBASIC.

  14. Worldwide satellite market demand forecast

    Science.gov (United States)

    Bowyer, J. M.; Frankfort, M.; Steinnagel, K. M.

    1981-01-01

    The forecast is for the years 1981 - 2000 with benchmark years at 1985, 1990 and 2000. Two typs of markets are considered for this study: Hardware (worldwide total) - satellites, earth stations and control facilities (includes replacements and spares); and non-hardware (addressable by U.S. industry) - planning, launch, turnkey systems and operations. These markets were examined for the INTELSAT System (international systems and domestic and regional systems using leased transponders) and domestic and regional systems. Forecasts were determined for six worldwide regions encompassing 185 countries using actual costs for existing equipment and engineering estimates of costs for advanced systems. Most likely (conservative growth rate estimates) and optimistic (mid range growth rate estimates) scenarios were employed for arriving at the forecasts which are presented in constant 1980 U.S. dollars. The worldwide satellite market demand forecast predicts that the market between 181 and 2000 will range from $35 to $50 billion. Approximately one-half of the world market, $16 to $20 billion, will be generated in the United States.

  15. Satellite Ozone Analysis Center (SOAC)

    International Nuclear Information System (INIS)

    Lovill, J.E.; Sullivan, T.J.; Knox, J.B.; Korver, J.A.

    1976-08-01

    Many questions have been raised during the 1970's regarding the possible modification of the ozonosphere by aircraft operating in the stratosphere. Concern also has been expressed over the manner in which the ozonosphere may change in the future as a result of fluorocarbon releases. There are also other ways by which the ozonosphere may be significantly altered, both anthropogenic and natural. Very basic questions have been raised, bearing upon the amount of ozone which would be destroyed by the NO/sub x/ produced in atmospheric nuclear explosions. Studies of the available satellite data have suggested that the worldwide increase of ozone during the past decade, which was observed over land stations, may have been biased by a poor distribution of stations and/or a shift of the planetary wave. Additional satellite data will be required to resolve this issue. Proposals are presented for monitoring of the Earth's ozone variability from the present time into the 1980's to establish a baseline upon which regional, as well as global, ozone trends can be measured

  16. Photometric Study of Uranian Satellites

    Science.gov (United States)

    Kesten, Philip R.

    1998-01-01

    The best summary of my work at NASA is expressed in the following abstract, submitted the Division for Planetary Science of the American Astronomical Society and to be presented at the annual meeting in Madison in October. We report photometric measurements of Uranian satellites Miranda, Ariel, Umbriel and Titania (10.4 Aug. 1995), and Neptune's satellite Triton (21.2 Sept. 1995) with the infrared camera (IRCAM) and standard J (1.13 - 1.42 microns), H (1.53 - 1.81 microns), and K (2.00 - 2.41 microns) filters at the 3.8-m UKIRT telescope on Mauna Kea. The individual images frames are 256 x 256 pixels with a platescale of .286 arcsec/pixel, resulting in a 1.22 arc min field of view. This summer brought the IR photometry measurements nearly to a close. As indicated by the abstract above, I will present this work at the annual DPS meeting in October. In anticipation of the opening of the new Carl Sagan Laboratory for Cosmochemisty, of which I will be a participating member, I also devoted a considerable fraction of the summer to learning the biochemistry which underlies the experiments to be conducted. To put the end of the summary close to the beginning, it was a most productive summer.

  17. Taiwan's second remote sensing satellite

    Science.gov (United States)

    Chern, Jeng-Shing; Ling, Jer; Weng, Shui-Lin

    2008-12-01

    FORMOSAT-2 is Taiwan's first remote sensing satellite (RSS). It was launched on 20 May 2004 with five-year mission life and a very unique mission orbit at 891 km altitude. This orbit gives FORMOSAT-2 the daily revisit feature and the capability of imaging the Arctic and Antarctic regions due to the high enough altitude. For more than three years, FORMOSAT-2 has performed outstanding jobs and its global effectiveness is evidenced in many fields such as public education in Taiwan, Earth science and ecological niche research, preservation of the world heritages, contribution to the International Charter: space and major disasters, observation of suspected North Korea and Iranian nuclear facilities, and scientific observation of the atmospheric transient luminous events (TLEs). In order to continue the provision of earth observation images from space, the National Space Organization (NSPO) of Taiwan started to work on the second RSS from 2005. This second RSS will also be Taiwan's first indigenous satellite. Both the bus platform and remote sensing instrument (RSI) shall be designed and manufactured by NSPO and the Instrument Technology Research Center (ITRC) under the supervision of the National Applied Research Laboratories (NARL). Its onboard computer (OBC) shall use Taiwan's indigenous LEON-3 central processing unit (CPU). In order to achieve cost effective design, the commercial off the shelf (COTS) components shall be widely used. NSPO shall impose the up-screening/qualification and validation/verification processes to ensure their normal functions for proper operations in the severe space environments.

  18. Transiting Exoplanet Survey Satellite (TESS)

    Science.gov (United States)

    Ricker, G. R.; Clampin, M.; Latham, D. W.; Seager, S.; Vanderspek, R. K.; Villasenor, J. S.; Winn, J. N.

    2012-01-01

    The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest stars in the sky. In a two-year survey, TESS will monitor more than 500,000 stars for temporary drops in brightness caused by planetary transits. This first-ever spaceborne all-sky transit survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances. No ground-based survey can achieve this feat. A large fraction of TESS target stars will be 30-100 times brighter than those observed by Kepler satellite, and therefore TESS . planets will be far easier to characterize with follow-up observations. TESS will make it possible to study the masses, sizes, densities, orbits, and atmospheres of a large cohort of small planets, including a sample of rocky worlds in the habitable zones of their host stars. TESS will provide prime targets for observation with the James Webb Space Telescope (JWST), as well as other large ground-based and space-based telescopes of the future. TESS data will be released with minimal delay (no proprietary period), inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the very nearest and brightest main-sequence stars hosting transiting exoplanets, thus providing future observers with the most favorable targets for detailed investigations.

  19. The Impact of Eclipsing GNSS Satellites on the Precise Point Positioning

    Directory of Open Access Journals (Sweden)

    Xinyun Cao

    2018-01-01

    Full Text Available When satellites enter into the noon maneuver or the shadow crossing regimes, the actual attitudes will depart from their nominal values. If improper attitude models are used, the induced-errors due to the wind-up effect and satellite antenna PCO (Phase Center Offset will deteriorate the positioning accuracy. Because different generations of satellites adopt different attitude control models, the influences on the positioning performances deserve further study. Consequently, the impact of three eclipsing strategies on the single-system and multi-GNSS (Global Navigation Satellite System Precise Point Positioning (PPP are analyzed. According to the results of the eclipsing monitor, 65 globally distributed MGEX (Multi-GNSS EXperiment stations for 31-day period in July 2017 are selected to perform G/R/E/C/GR/GREC PPP in both static and kinematic modes. The results show that the influences of non-nominal attitudes are related to the magnitude of the PCO values, maximum yaw angle differences, the duration of maneuver, the value of the sun angle and the satellite geometric strength. For single-system, using modeled attitudes rather than the nominal ones will greatly improve the positioning accuracy of GLONASS-only and BDS-only PPP while slightly contributions to the GPS-only and GALILEO-only PPP. Deleting the eclipsing satellites may sometimes induce a longer convergence time and a worse solution due to the poor satellite geometry, especially for GLONASS kinematic PPP when stations are located in the low latitude and BDS kinematic PPP. When multi-GNSS data are available, especially four navigation systems, the accuracy improvements of using the modeled attitudes or deleting eclipsing satellites are non-significant.

  20. Blossom Point Satellite Tracking and Command Station

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: The Blossom Point Satellite Command and Tracking Facility (BP) provides engineering and operational support to several complex space systems for the Navy...

  1. Satellite recovery - Attitude dynamics of the targets

    Science.gov (United States)

    Cochran, J. E., Jr.; Lahr, B. S.

    1986-01-01

    The problems of categorizing and modeling the attitude dynamics of uncontrolled artificial earth satellites which may be targets in recovery attempts are addressed. Methods of classification presented are based on satellite rotational kinetic energy, rotational angular momentum and orbit and on the type of control present prior to the benign failure of the control system. The use of approximate analytical solutions and 'exact' numerical solutions to the equations governing satellite attitude motions to predict uncontrolled attitude motion is considered. Analytical and numerical results are presented for the evolution of satellite attitude motions after active control termination.

  2. Advanced Deployable Structural Systems for Small Satellites

    Science.gov (United States)

    Belvin, W. Keith; Straubel, Marco; Wilkie, W. Keats; Zander, Martin E.; Fernandez, Juan M.; Hillebrandt, Martin F.

    2016-01-01

    One of the key challenges for small satellites is packaging and reliable deployment of structural booms and arrays used for power, communication, and scientific instruments. The lack of reliable and efficient boom and membrane deployment concepts for small satellites is addressed in this work through a collaborative project between NASA and DLR. The paper provides a state of the art overview on existing spacecraft deployable appendages, the special requirements for small satellites, and initial concepts for deployable booms and arrays needed for various small satellite applications. The goal is to enhance deployable boom predictability and ground testability, develop designs that are tolerant of manufacturing imperfections, and incorporate simple and reliable deployment systems.

  3. Live Satellite Communications... An Exciting Teaching Aid

    Science.gov (United States)

    Journal of Aerospace Education, 1976

    1976-01-01

    Describes ways that orbiting satellites carrying amateur radios can be used in the classroom at various grade levels to supplement physics, mathematics, electronics, and social science curricula. (MLH)

  4. Interim Service ISDN Satellite (ISIS) simulator development for advanced satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The simulation development associated with the network models of both the Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) and the Full Service ISDN Satellite (FSIS) architectures is documented. The ISIS Network Model design represents satellite systems like the Advanced Communications Technology Satellite (ACTS) orbiting switch. The FSIS architecture, the ultimate aim of this element of the Satellite Communications Applications Research (SCAR) Program, moves all control and switching functions on-board the next generation ISDN communications satellite. The technical and operational parameters for the advanced ISDN communications satellite design will be obtained from the simulation of ISIS and FSIS engineering software models for their major subsystems. Discrete event simulation experiments will be performed with these models using various traffic scenarios, design parameters, and operational procedures. The data from these simulations will be used to determine the engineering parameters for the advanced ISDN communications satellite.

  5. Hurricane Satellite (HURSAT) from International Satellite Cloud Climatology Project (ISCCP) B1, Version 6

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Hurricane Satellite (HURSAT) from derived International Satellite Cloud Climatology Project (ISCCP) B1 observations of tropical cyclones worldwide. The B1 data...

  6. The population of natural Earth satellites

    Science.gov (United States)

    Granvik, Mikael; Vaubaillon, Jeremie; Jedicke, Robert

    2012-03-01

    We have for the first time calculated the population characteristics of the Earth’s irregular natural satellites (NESs) that are temporarily captured from the near-Earth-object (NEO) population. The steady-state NES size-frequency and residence-time distributions were determined under the dynamical influence of all the massive bodies in the Solar System (but mainly the Sun, Earth, and Moon) for NEOs of negligible mass. To this end, we compute the NES capture probability from the NEO population as a function of the latter’s heliocentric orbital elements and combine those results with the current best estimates for the NEO size-frequency and orbital distribution. At any given time there should be at least one NES of 1-m diameter orbiting the Earth. The average temporarily-captured orbiter (TCO; an object that makes at least one revolution around the Earth in a co-rotating coordinate system) completes (2.88 ± 0.82) rev around the Earth during a capture event that lasts (286 ± 18) d. We find a small preference for capture events starting in either January or July. Our results are consistent with the single known natural TCO, 2006 RH120, a few-meter diameter object that was captured for about a year starting in June 2006. We estimate that about 0.1% of all meteors impacting the Earth were TCOs.

  7. Satellite cell proliferation in adult skeletal muscle

    Science.gov (United States)

    Booth, Frank W. (Inventor); Thomason, Donald B. (Inventor); Morrison, Paul R. (Inventor); Stancel, George M. (Inventor)

    1995-01-01

    Novel methods of retroviral-mediated gene transfer for the in vivo corporation and stable expression of eukaryotic or prokaryotic foreign genes in tissues of living animals is described. More specifically, methods of incorporating foreign genes into mitotically active cells are disclosed. The constitutive and stable expression of E. coli .beta.-galactosidase gene under the promoter control of the Moloney murine leukemia virus long terminal repeat is employed as a particularly preferred embodiment, by way of example, establishes the model upon which the incorporation of a foreign gene into a mitotically-active living eukaryotic tissue is based. Use of the described methods in therapeutic treatments for genetic diseases, such as those muscular degenerative diseases, is also presented. In muscle tissue, the described processes result in genetically-altered satellite cells which proliferate daughter myoblasts which preferentially fuse to form a single undamaged muscle fiber replacing damaged muscle tissue in a treated animal. The retroviral vector, by way of example, includes a dystrophin gene construct for use in treating muscular dystrophy. The present invention also comprises an experimental model utilizable in the study of the physiological regulation of skeletal muscle gene expression in intact animals.

  8. Economics of satellite communications systems

    Science.gov (United States)

    Pritchard, Wilbur L.

    This paper is partly a tutorial, telling systematically how one goes about calculating the total annual costs of a satellite communications system, and partly the expression of some original ideas on the choice of parameters so as to minimize these costs. The calculation of costs can be divided into two broad categories. The first is technical and is concerned with estimating what particular equipment will cost and what will be the annual expense to maintain and operate it. One starts in the estimation of any new system by listing the principal items of equipment, such as satellites, earth stations of various sizes and functions, telemetry and tracking equipment and terrestrial interfaces, and then estimating how much each item will cost. Methods are presented for generating such estimates, based on a knowledge of the gross parameters, such as antenna size, coverage area, transmitter power and information rate. These parameters determine the system performance and it is usually possible, knowing them, to estimate the costs of the equipment rather well. Some formulae based on regression analyses are presented. Methods are then given for estimating closely related expenses, such as maintenance and operation, and then an approximate method is developed for estimating terrestrial interconnection costs. It is pointed out that in specific cases when tariff and geographical information are available, it is usually better to work with specific data, but nonetheless it is often desirable, especially in global system estimating, to approximate these interconnect costs without recourse to individual tariffs. The procedure results in a set of costs for the purchase of equipment and its maintenance, and a schedule of payments. Some payments will be incurred during the manufacture of the satellite and before any systems operation, but many will not be incurred until the system is no longer in use, e.g. incentives. In any case, with the methods presented in the first section, one

  9. JPSS Preparations at the Satellite Proving Ground for Marine, Precipitation, and Satellite Analysis

    Science.gov (United States)

    Folmer, Michael J.; Berndt, E.; Clark, J.; Orrison, A.; Kibler, J.; Sienkiewicz, J.; Nelson, J.; Goldberg, M.; Sjoberg, W.

    2016-01-01

    The ocean prediction center at the national hurricane center's tropical analysis and forecast Branch, the Weather Prediction center and the Satellite analysis branch of NESDIS make up the Satellite Proving Ground for Marine, Precipitation and Satellite Analysis. These centers had early exposure to JPSS products using the S-NPP Satellite that was launched in 2011. Forecasters continue to evaluate new products in anticipation for the launch of JPSS-1 sometime in 2017.

  10. Full Service ISDN Satellite (FSIS) network model for advanced ISDN satellite design and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The Full Service Integrated Services Digital Network (FSIS) network model for advanced satellite designs describes a model suitable for discrete event simulations. A top down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ACTS and the Interim Service ISDN Satellite (ISIS) perform ISDN protocol analyses and switching decisions in the terrestrial domain, whereas FSIS makes all its analyses and decisions on-board the ISDN satellite.

  11. New perspectives for high accuracy SLR with second generation geodesic satellites

    Science.gov (United States)

    Lund, Glenn

    1993-01-01

    This paper reports on the accuracy limitations imposed by geodesic satellite signatures, and on the potential for achieving millimetric performances by means of alternative satellite concepts and an optimized 2-color system tradeoff. Long distance laser ranging, when performed between a ground (emitter/receiver) station and a distant geodesic satellite, is now reputed to enable short arc trajectory determinations to be achieved with an accuracy of 1 to 2 centimeters. This state-of-the-art accuracy is limited principally by the uncertainties inherent to single-color atmospheric path length correction. Motivated by the study of phenomena such as postglacial rebound, and the detailed analysis of small-scale volcanic and strain deformations, the drive towards millimetric accuracies will inevitably be felt. With the advent of short pulse (less than 50 ps) dual wavelength ranging, combined with adequate detection equipment (such as a fast-scanning streak camera or ultra-fast solid-state detectors) the atmospheric uncertainty could potentially be reduced to the level of a few millimeters, thus, exposing other less significant error contributions, of which by far the most significant will then be the morphology of the retroreflector satellites themselves. Existing geodesic satellites are simply dense spheres, several 10's of cm in diameter, encrusted with a large number (426 in the case of LAGEOS) of small cube-corner reflectors. A single incident pulse, thus, results in a significant number of randomly phased, quasi-simultaneous return pulses. These combine coherently at the receiver to produce a convolved interference waveform which cannot, on a shot to shot basis, be accurately and unambiguously correlated to the satellite center of mass. This paper proposes alternative geodesic satellite concepts, based on the use of a very small number of cube-corner retroreflectors, in which the above difficulties are eliminated while ensuring, for a given emitted pulse, the return

  12. Molecular analysis and genomic organization of major DNA satellites in banana (Musa spp.).

    Science.gov (United States)

    Čížková, Jana; Hřibová, Eva; Humplíková, Lenka; Christelová, Pavla; Suchánková, Pavla; Doležel, Jaroslav

    2013-01-01

    Satellite DNA sequences consist of tandemly arranged repetitive units up to thousands nucleotides long in head-to-tail orientation. The evolutionary processes by which satellites arise and evolve include unequal crossing over, gene conversion, transposition and extra chromosomal circular DNA formation. Large blocks of satellite DNA are often observed in heterochromatic regions of chromosomes and are a typical component of centromeric and telomeric regions. Satellite-rich loci may show specific banding patterns and facilitate chromosome identification and analysis of structural chromosome changes. Unlike many other genomes, nuclear genomes of banana (Musa spp.) are poor in satellite DNA and the information on this class of DNA remains limited. The banana cultivars are seed sterile clones originating mostly from natural intra-specific crosses within M. acuminata (A genome) and inter-specific crosses between M. acuminata and M. balbisiana (B genome). Previous studies revealed the closely related nature of the A and B genomes, including similarities in repetitive DNA. In this study we focused on two main banana DNA satellites, which were previously identified in silico. Their genomic organization and molecular diversity was analyzed in a set of nineteen Musa accessions, including representatives of A, B and S (M. schizocarpa) genomes and their inter-specific hybrids. The two DNA satellites showed a high level of sequence conservation within, and a high homology between Musa species. FISH with probes for the satellite DNA sequences, rRNA genes and a single-copy BAC clone 2G17 resulted in characteristic chromosome banding patterns in M. acuminata and M. balbisiana which may aid in determining genomic constitution in interspecific hybrids. In addition to improving the knowledge on Musa satellite DNA, our study increases the number of cytogenetic markers and the number of individual chromosomes, which can be identified in Musa.

  13. The Scattering Properties of Natural Terrestrial Snows versus Icy Satellite Surfaces

    Science.gov (United States)

    Domingue, Deborah; Hartman, Beth; Verbiscer, Anne

    1997-01-01

    Our comparisons of the single particle scattering behavior of terrestrial snows and icy satellite regoliths to the laboratory particle scattering measurements of McGuire and Hapke demonstrate that the differences between icy satellite regoliths and their terrestrial counterparts are due to particle structures and textures. Terrestrial snow particle structures define a region in the single particle scattering function parameter space separate from the regions defined by the McGuire and Hapke artificial laboratory particles. The particle structures and textures of the grains composing icy satellites regoliths are not simple or uniform but consist of a variety of particle structure and texture types, some of which may be a combination of the particle types investigated by McGuire and Hapke.

  14. Science operations management. [with Infrared Astronomy Satellite project

    Science.gov (United States)

    Squibb, G. F.

    1984-01-01

    The operation teams engaged in the IR Astronomical Satellite (IRAS) project included scientists from the IRAS International Science Team. The detailed involvement of these scientists in the design, testing, validation, and operations phases of the IRAS mission contributed to the success of this project. The Project Management Group spent a substantial amount of time discussing science-related issues, because science team coleaders were members from the outset. A single scientific point-of-contact for the Management Group enhanced the depth and continuity of agreement reached in decision-making.

  15. Transient SEU characterization of analog IC's for ESA's satellite

    International Nuclear Information System (INIS)

    Harboe-Soerensen, R.; Van Dooren, J.; Guerre, F.X.; Constans, H.; Berger, G.; Hajdas, W.

    1999-01-01

    Data analysis of four self switch-off power supply events in the SOHO satellite pointed strongly in the direction of being Cosmic Ray or Proton induced. Further analysis of the relevant power supply schematics identified a number of analog IC's capable of causing or contributing to such events. This paper concentrates on the testing aspects of these analog IC's and presents the results of a Single Event Effects (SEEs) test program. Ground testing, simulating the flight conditions, were carried out at both heavy ion and proton accelerators. (authors)

  16. The impact of curved satellite tracks on SAR focusing

    DEFF Research Database (Denmark)

    Mohr, Johan Jacob; Madsen, Søren Nørvang

    2000-01-01

    This paper addresses the geometric effect of processing single look complex synthetic aperture radar (SAR) data to a reference squint angle different from that given by the center of the real antenna beam. For data acquired on a straight flight line, the required transformation of radar coordinat...... from one Doppler reference to another is independent of the target elevation but for data acquired from a satellite orbit over a rotating Earth that is not true. Also the effect of ignoring Earth rotation is addressed....

  17. Why is CDMA the solution for mobile satellite communication

    Science.gov (United States)

    Gilhousen, Klein S.; Jacobs, Irwin M.; Padovani, Roberto; Weaver, Lindsay A.

    1989-01-01

    It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems. Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment. Results of extensive computer simulations as well as laboratory and field tests results are presented.

  18. Singled out?

    Science.gov (United States)

    Waller, Frank

    2004-03-01

    The increasing use of single use medical devices is being driven by a growing awareness of iatrogenic (from the Greek; caused by the doctor) and nosocomial infections. Public health perceptions relating to transmissible spongiform encephalopathies, specifically variant Creutzfeldt-Jakob disease (vCJD), the Human Immunodeficiency Virus (HIV) and Hepatitis B are high on the political agenda and a matter of concern to healthcare professionals.

  19. The Strategic Nature of the Tactical Satellite. Part 2

    Science.gov (United States)

    2006-08-13

    engagement. Again, the myth of the tactical satellite is that they are tactical. Calling a dandelion a rose doesn’t change its smell. As former...a scary satellite weapon called a ‘parasite satellite.’ This is a micro- satellite that could attach itself to just about any type of satellite with

  20. Midday values of gross CO2 flux and light use efficiency during satellite overpasses can be used to directly estimate eight-day mean flux

    Science.gov (United States)

    Daniel A. Sims; Abdullah F. Rahman; Vicente D. Cordova; Dennis D. Baldocchi; Lawrence B. Flanagan; Allen H. Goldstein; David Y. Hollinger; Laurent Misson; Russell K. Monson; Hans P. Schmid; Steven C. Wofsy; Liukang Xu

    2005-01-01

    Most satellites provide, at best, a single daily snapshot of vegetation and, at worst, these snapshots may be separated by periods of many days when the ground was obscured by cloud cover. Since vegetation carbon exchange can be very dynamic on diurnal and day-to-day timescales, the limited temporal resolution of satellite data is a potential limitation in the use of...

  1. Digital optical feeder links system for broadband geostationary satellite

    Science.gov (United States)

    Poulenard, Sylvain; Mège, Alexandre; Fuchs, Christian; Perlot, Nicolas; Riedi, Jerome; Perdigues, Josep

    2017-02-01

    An optical link based on a multiplex of wavelengths at 1.55μm is foreseen to be a valuable solution for the feeder link of the next generation of high-throughput geostationary satellite. The main satellite operator specifications for such link are an availability of 99.9% over the year, a capacity around 500Gbit/s and to be bent-pipe. Optical ground station networks connected to Terabit/s terrestrial fibers are proposed. The availability of the optical feeder link is simulated over 5 years based on a state-of-the-art cloud mask data bank and an atmospheric turbulence strength model. Yearly and seasonal optical feeder link availabilities are derived and discussed. On-ground and on-board terminals are designed to be compliant with 10Gbit/s per optical channel data rate taking into account adaptive optic systems to mitigate the impact of atmospheric turbulences on single-mode optical fiber receivers. The forward and return transmission chains, concept and implementation, are described. These are based on a digital transparent on-off keying optical link with digitalization of the DVB-S2 and DVB-RCS signals prior to the transmission, and a forward error correcting code. In addition, the satellite architecture is described taking into account optical and radiofrequency payloads as well as their interfaces.

  2. Nano-Satellite Secondary Spacecraft on Deep Space Missions

    Science.gov (United States)

    Klesh, Andrew T.; Castillo-Rogez, Julie C.

    2012-01-01

    NanoSat technology has opened Earth orbit to extremely low-cost science missions through a common interface that provides greater launch accessibility. They have also been used on interplanetary missions, but these missions have used one-off components and architectures so that the return on investment has been limited. A natural question is the role that CubeSat-derived NanoSats could play to increase the science return of deep space missions. We do not consider single instrument nano-satellites as likely to complete entire Discovery-class missions alone,but believe that nano-satellites could augment larger missions to significantly increase science return. The key advantages offered by these mini-spacecrafts over previous planetary probes is the common availability of advanced subsystems that open the door to a large variety of science experiments, including new guidance, navigation and control capabilities. In this paper, multiple NanoSat science applications are investigated, primarily for high risk/high return science areas. We also address the significant challenges and questions that remain as obstacles to the use of nano-satellites in deep space missions. Finally, we provide some thoughts on a development roadmap toward interplanetary usage of NanoSpacecraft.

  3. Solar radio proxies for improved satellite orbit prediction

    Science.gov (United States)

    Yaya, Philippe; Hecker, Louis; Dudok de Wit, Thierry; Fèvre, Clémence Le; Bruinsma, Sean

    2017-12-01

    Specification and forecasting of solar drivers to thermosphere density models is critical for satellite orbit prediction and debris avoidance. Satellite operators routinely forecast orbits up to 30 days into the future. This requires forecasts of the drivers to these orbit prediction models such as the solar Extreme-UV (EUV) flux and geomagnetic activity. Most density models use the 10.7 cm radio flux (F10.7 index) as a proxy for solar EUV. However, daily measurements at other centimetric wavelengths have also been performed by the Nobeyama Radio Observatory (Japan) since the 1950's, thereby offering prospects for improving orbit modeling. Here we present a pre-operational service at the Collecte Localisation Satellites company that collects these different observations in one single homogeneous dataset and provides a 30 days forecast on a daily basis. Interpolation and preprocessing algorithms were developed to fill in missing data and remove anomalous values. We compared various empirical time series prediction techniques and selected a multi-wavelength non-recursive analogue neural network. The prediction of the 30 cm flux, and to a lesser extent that of the 10.7 cm flux, performs better than NOAA's present prediction of the 10.7 cm flux, especially during periods of high solar activity. In addition, we find that the DTM-2013 density model (Drag Temperature Model) performs better with (past and predicted) values of the 30 cm radio flux than with the 10.7 flux.

  4. Whales from space: counting southern right whales by satellite.

    Science.gov (United States)

    Fretwell, Peter T; Staniland, Iain J; Forcada, Jaume

    2014-01-01

    We describe a method of identifying and counting whales using very high resolution satellite imagery through the example of southern right whales breeding in part of the Golfo Nuevo, Península Valdés in Argentina. Southern right whales have been extensively hunted over the last 300 years and although numbers have recovered from near extinction in the early 20(th) century, current populations are fragmented and are estimated at only a small fraction of pre-hunting total. Recent extreme right whale calf mortality events at Península Valdés, which constitutes the largest single population, have raised fresh concern for the future of the species. The WorldView2 satellite has a maximum 50 cm resolution and a water penetrating coastal band in the far-blue part of the spectrum that allows it to see deeper into the water column. Using an image covering 113 km², we identified 55 probable whales and 23 other features that are possibly whales, with a further 13 objects that are only detected by the coastal band. Comparison of a number of classification techniques, to automatically detect whale-like objects, showed that a simple thresholding technique of the panchromatic and coastal band delivered the best results. This is the first successful study using satellite imagery to count whales; a pragmatic, transferable method using this rapidly advancing technology that has major implications for future surveys of cetacean populations.

  5. Groebner Basis Solutions to Satellite Trajectory Control by Pole Placement

    Science.gov (United States)

    Kukelova, Z.; Krsek, P.; Smutny, V.; Pajdla, T.

    2013-09-01

    Satellites play an important role, e.g., in telecommunication, navigation and weather monitoring. Controlling their trajectories is an important problem. In [1], an approach to the pole placement for the synthesis of a linear controller has been presented. It leads to solving five polynomial equations in nine unknown elements of the state space matrices of a compensator. This is an underconstrained system and therefore four of the unknown elements need to be considered as free parameters and set to some prior values to obtain a system of five equations in five unknowns. In [1], this system was solved for one chosen set of free parameters with the help of Dixon resultants. In this work, we study and present Groebner basis solutions to this problem of computation of a dynamic compensator for the satellite for different combinations of input free parameters. We show that the Groebner basis method for solving systems of polynomial equations leads to very simple solutions for all combinations of free parameters. These solutions require to perform only the Gauss-Jordan elimination of a small matrix and computation of roots of a single variable polynomial. The maximum degree of this polynomial is not greater than six in general but for most combinations of the input free parameters its degree is even lower. [1] B. Palancz. Application of Dixon resultant to satellite trajectory control by pole placement. Journal of Symbolic Computation, Volume 50, March 2013, Pages 79-99, Elsevier.

  6. Satellite NMR in Cu doped with transition impurities

    International Nuclear Information System (INIS)

    Slichter, C.P.

    1979-01-01

    Measurements were made of the conduction electron spin magnetization density, M/sub sigma/(R vector) near iron group atoms (Sc through Ni) in Cu. M/sub sigma/(R vector) produces an additional effective local field which shifts the NMR frequency of nearby shells of Cu nuclei relative to Cu nuclei far from all impurities. Resonances of nearby shells appear as weak satellites to the strong resonance of distant Cu nuclei (the main line). M/sub sigma/(R vector) at a given site is proportional through know constants to the splitting of the satellite from the main line. The shell was identified giving rise to the satellite in many cases by use of single crystals. A good approximation M/sub sigma/(R vector) is proportional to the spin susceptibility chi/sub s/ of the impurity. For CuCr we find a large temperature independent chi/sub s/, in contrast to CuMn and CuFe. The results lead to a picture of the electronic structure of Cr, Mn, and Fe along the lines of Schrieffer and Hirst as ions with integral numbers of d-electrons, possessing crystal field and spin-orbit couplings

  7. Generating Land Surface Reflectance for the New Generation of Geostationary Satellite Sensors with the MAIAC Algorithm

    Science.gov (United States)

    Wang, W.; Wang, Y.; Hashimoto, H.; Li, S.; Takenaka, H.; Higuchi, A.; Lyapustin, A.; Nemani, R. R.

    2017-12-01

    The latest generation of geostationary satellite sensors, including the GOES-16/ABI and the Himawari 8/AHI, provide exciting capability to monitor land surface at very high temporal resolutions (5-15 minute intervals) and with spatial and spectral characteristics that mimic the Earth Observing System flagship MODIS. However, geostationary data feature changing sun angles at constant view geometry, which is almost reciprocal to sun-synchronous observations. Such a challenge needs to be carefully addressed before one can exploit the full potential of the new sources of data. Here we take on this challenge with Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm, recently developed for accurate and globally robust applications like the MODIS Collection 6 re-processing. MAIAC first grids the top-of-atmosphere measurements to a fixed grid so that the spectral and physical signatures of each grid cell are stacked ("remembered") over time and used to dramatically improve cloud/shadow/snow detection, which is by far the dominant error source in the remote sensing. It also exploits the changing sun-view geometry of the geostationary sensor to characterize surface BRDF with augmented angular resolution for accurate aerosol retrievals and atmospheric correction. The high temporal resolutions of the geostationary data indeed make the BRDF retrieval much simpler and more robust as compared with sun-synchronous sensors such as MODIS. As a prototype test for the geostationary-data processing pipeline on NASA Earth Exchange (GEONEX), we apply MAIAC to process 18 months of data from Himawari 8/AHI over Australia. We generate a suite of test results, including the input TOA reflectance and the output cloud mask, aerosol optical depth (AOD), and the atmospherically-corrected surface reflectance for a variety of geographic locations, terrain, and land cover types. Comparison with MODIS data indicates a general agreement between the retrieved surface reflectance

  8. Space Access for Small Satellites on the K-1

    Science.gov (United States)

    Faktor, L.

    Affordable access to space remains a major obstacle to realizing the increasing potential of small satellites systems. On a per kilogram basis, small launch vehicles are simply too expensive for the budgets of many small satellite programs. Opportunities for rideshare with larger payloads on larger launch vehicles are still rare, given the complications associated with coordinating delivery schedules and deployment orbits. Existing contractual mechanisms are also often inadequate to facilitate the launch of multiple payload customers on the same flight. Kistler Aerospace Corporation is committed to lowering the price and enhancing the availability of space access for small satellite programs through the fully-reusable K-1 launch vehicle. Kistler has been working with a number of entities, including Astrium Ltd., AeroAstro, and NASA, to develop innovative approaches to small satellite missions. The K-1 has been selected by NASA as a Flight Demonstration Vehicle for the Space Launch Initiative. NASA has purchased the flight results during the first four K-1 launches on the performance of 13 advanced launch vehicle technologies embedded in the K-1 vehicle. On K-1 flights #2-#4, opportunities exist for small satellites to rideshare to low-earth orbit for a low-launch price. Kistler's flight demonstration contract with NASA also includes options to fly Add-on Technology Experiment flights. Opportunities exist for rideshare payloads on these flights as well. Both commercial and government customers may take advantage of the rideshare pricing. Kistler is investigating the feasibility of flying dedicated, multiple small payload missions. Such a mission would launch multiple small payloads from a single customer or small payloads from different customers. The orbit would be selected to be compatible with the requirements of as many small payload customers as possible, and make use of reusable hardware, standard interfaces (such as the existing MPAS) and verification plans

  9. Study of chaos in chaotic satellite systems

    Indian Academy of Sciences (India)

    Ayub Khan

    2017-12-27

    Dec 27, 2017 ... through strange attractor which is framed of the com- plex patterns. The one ... jectory of the Slave satellite be the measured attitude of the Master satellite [12 ... Bifurcation occurs when a tiny smooth change is made to the parameter .... negative and one of these tends to zero which is the required condition ...

  10. IMPLEMENTATION OF AERONAUTICAL LOCAL SATELLITE AUGMENTATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Stojce Ilcev

    2011-03-01

    Full Text Available Abstract. This paper introduces development and implementation of new Local Satellite AugmentationSystem as an integration component of the Regional Satellite Augmentation System (RSAS employingcurrent and new Satellite Communications, Navigation and Surveillance (CNS for improvement of the AirTraffic Control (ATC and Air Traffic Management (ATM and for enhancement safety systems includingtransport security and control of flights in all stages, airport approaching, landing, departures and allmovements over airport surface areas. The current first generation of the Global Navigation Satellite SystemGNSS-1 applications are represented by fundamental military solutions for Position, Velocity and Time ofthe satellite navigation and determination systems such as the US GPS and Russian GLONASS (Former-USSR requirements, respectively. The establishment of Aeronautical CNS is also discussed as a part ofGlobal Satellite Augmentation Systems of GPS and GLONASS systems integrated with existing and futureRSAS and LSAS in airports areas. Specific influence and factors related to the Comparison of the Currentand New Aeronautical CNS System including the Integration of RSAS and GNSS solutions are discussedand packet of facts is determined to maximize the new satellite Automatic Dependent Surveillance System(ADSS and Special Effects of the RSAS Networks. The possible future integration of RSAS and GNSS andthe common proposal of the satellite Surface Movement Guidance and Control are presented in thechangeless ways as of importance for future enfacements of ATC and ATM for any hypothetical airportinfrastructure.Keywords: ADSS, ATC, ATM, CNS, GSAS, LRAS, RSAS, SMGC, Special Effects of RSAS.

  11. Study of chaos in chaotic satellite systems

    Indian Academy of Sciences (India)

    Lyapunov exponents are estimated. From these studies, chaosin satellite system has been established. Solution of equations of motion of the satellite system are drawn in the form of three-dimensional, two-dimensional and time series phase portraits. Phase portraits and time series display the chaotic nature of the ...

  12. Swarm Satellites : Design, Characteristics and Applications

    NARCIS (Netherlands)

    Engelen, S.

    2016-01-01

    Satellite swarms are a novelty, yet promise to deliver unprecedented robustness and data-collection efficiency. They are so new in fact that even the definition of what a satellite swarm is is disputable, and consequently, the term "swarm" is used for practically any type of distributed space

  13. Satellite Remote Sensing in Offshore Wind Energy

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Badger, Merete; Astrup, Poul

    2013-01-01

    Satellite remote sensing of ocean surface winds are presented with focus on wind energy applications. The history on operational and research-based satellite ocean wind mapping is briefly described for passive microwave, scatterometer and synthetic aperture radar (SAR). Currently 6 GW installed...

  14. Nanosatellite swarm support for larger satellites

    NARCIS (Netherlands)

    Verhoeven, Chris; Engelen, Steven; Noroozi, Arash; Bentum, Marinus Jan; Sundaramoorthy, Prem; Meijer, Robert

    2011-01-01

    Nano-satellites are small (less than 10 kg) and low cost satellites of which quite a number has been launched the last few years, mostly as university educational or research projects. The development of professional scientific and commercial applications is still in its infancy and there are only

  15. Fiber optic sensing for telecommunication satellites

    Science.gov (United States)

    Reutlinger, Arnd; Glier, Markus; Zuknik, Karl-Heinz; Hoffmann, Lars; Müller, Mathias; Rapp, Stephan; Kurvin, Charles; Ernst, Thomas; McKenzie, Iain; Karafolas, Nikos

    2017-11-01

    Modern telecommunication satellites can benefit from the features of fiber optic sensing wrt to mass savings, improved performance and lower costs. Within the course of a technology study, launched by the European Space Agency, a fiber optic sensing system has been designed and is to be tested on representative mockups of satellite sectors and environment.

  16. Data distribution in the OLFAR satellite swarm

    NARCIS (Netherlands)

    Budianu, A.; Willink-Castro, T.J.; Engelen, S.; Rajan, R.T.; Rajan, Raj; Smith, D.M.P.; Meijerink, Arjan; Bentum, Marinus Jan

    2013-01-01

    The Orbiting Low Frequency Antennas for Radio Astronomy (OLFAR) project aims to develop a radio telescope for very low frequencies (below 30 MHz) by using a swarm of 50 or more nano-satellites. Spread in a 100-km diameter cloud, the satellites will form a very large aperture capable of sensing the

  17. SOVCAN STAR: An international satellite system

    Science.gov (United States)

    Skatchkov, Valery A.

    SOVCAN STAR is a Russian-Canadian cooperative venture company formed to manufacture, test, launch and operate a Ku-band satellite system. Drawing on the more than twenty years communications satellite experience of the founding companies, the SOVCAN STAR satellites are being designed to be competitive and cost effective. They will be equipped with 24 transponders and four steerable antennas. The design allows the operators to switch individual transponders between the various antenna coverage beams. These satellites will offer a high degree of operational flexibility and performance. The SOVCAN STAR strategy is to develop a network of satellites in parallel with the growth and evolution of the traffic requirements. Such an approach minimizes the technical, schedule and program risks while at the same time significantly reduces the financial exposure. The first SOVCAN STAR satellite will be commissioned in 1996 and operated at 14 deg W. The beams will be aligned to North America and Europe offering International service between Canada, the Eastern U.S.A., Europe, Russia and the Western C.I.S. Republics. The second SOVCAN STAR satellite will be commissioned a year later and operated at 145 deg E. This satellite will cover the Western Pacific Ocean, Eastern Asia and Australasia.

  18. Satellite Sanitary Systems in Kampala, Uganda

    NARCIS (Netherlands)

    Letema, S.C.; Vliet, van B.J.M.; Lier, van J.B.

    2012-01-01

    Satellite sewage collection and treatment systems have been independently developed and managed in East African cities outside the centrally planned and sewered areas. A satellite approach is a promising provisioning option parallel to public sewerage for middle- and high-income residential areas,

  19. Satellite Sanitary Systems in Kampala, Uganda

    NARCIS (Netherlands)

    Letema, S.; Van Vliet, B.; Van Lier, J.B.

    2011-01-01

    Satellite sewage collection and treatment systems have been independently developed and managed in East African cities outside the centrally planned and sewered areas. A satellite approach is a promising provisioning option parallel to public sewerage for middle- and high-income residential areas,

  20. Astrophysics with small satellites in Scandinavia

    DEFF Research Database (Denmark)

    Lund, Niels

    2003-01-01

    The small-satellites activities in the Scandinavian countries are briefly surveyed with emphasis on astrophysics research. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.......The small-satellites activities in the Scandinavian countries are briefly surveyed with emphasis on astrophysics research. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved....

  1. Satellite Communication and Development: A Reassessment.

    Science.gov (United States)

    Hudson, Heather E.

    The potential benefits of satellite communications development have been recognized since the notion of a geostationary "space platform" was proposed by Arthur C. Clarke in 1945. Although there have been examples of developmental applications of satellite technology, the promise has been slow in being fulfilled. The history of the…

  2. The Direct Satellite Connection: Definitions and Prospects.

    Science.gov (United States)

    Wigand, Rolf T.

    1980-01-01

    Defines direct satellite broadcasting as the transmission of broadcast signals via high-powered satellites that permit direct reception of television or radio programs by means of small antennas. Outlines American, European, and Japanese plans for direct-to-home television reception and implications for the broadcasting industry. (JMF)

  3. Interim Service ISDN Satellite (ISIS) hardware experiment development for advanced ISDN satellite designs and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The Interim Service Integrated Service Digital Network (ISDN) Satellite (ISIS) Hardware Experiment Development for Advanced Satellite Designs describes the development of the ISDN Satellite Terminal Adapter (ISTA) capable of translating ISDN protocol traffic into Time Division Multiple Access (TDMA) signals for use by a communications satellite. The ISTA connects the Type 1 Network Termination (NT1) via the U-interface on the line termination side of the CPE to the RS-499 interface for satellite uplink. The same ISTA converts in the opposite direction the RS-499 to U-interface data with a simple switch setting.

  4. Interim Service ISDN Satellite (ISIS) hardware experiment design for advanced ISDN satellite design and experiments

    Science.gov (United States)

    Pepin, Gerard R.

    1992-01-01

    The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Hardware Experiment Design for Advanced Satellite Designs describes the design of the ISDN Satellite Terminal Adapter (ISTA) capable of translating ISDN protocol traffic into time division multiple access (TDMA) signals for use by a communications satellite. The ISTA connects the Type 1 Network Termination (NT1) via the U-interface on the line termination side of the CPE to the V.35 interface for satellite uplink. The same ISTA converts in the opposite direction the V.35 to U-interface data with a simple switch setting.

  5. High power communication satellites power systems study

    International Nuclear Information System (INIS)

    Josloff, A.T.; Peterson, J.R.

    1994-01-01

    This paper discusses a DOE-funded study to evaluate the commercial attractiveness of high power communication satellites and assesses the attributes of both conventional photovoltaic and reactor power systems. This study brings together a preeminent US Industry/Russian team to cooperate on the role of high power communication satellites in the rapidly expanding communications revolution. These high power satellites play a vital role in assuring availability of universally accessible, wide bandwidth communications, for high definition TV, super computer networks and other services. Satellites are ideally suited to provide the wide bandwidths and data rates required and are unique in the ability to provide services directly to the users. As new or relocated markets arise, satellites offer a flexibility that conventional distribution services cannot match, and it is no longer necessary to be near population centers to take advantage of the telecommunication revolution. The geopolitical implications of these substantially enhanced communications capabilities will be significant

  6. Temperature diagnostics using lithium-like satellites

    International Nuclear Information System (INIS)

    Datla, R.U.; Jones, L.A.; Thomson, D.B.

    1980-10-01

    A 60-kJ theta-pinch was operated at a filling pressure of 16 mtorr using a gas mixture of 2% neon and 98% helium. The resonance and intercombination lines from Ne IX and the Li-like satellites were observed with a Bragg crystal monochromator. The electron temperature of the plasma was deduced from the intensity ratios of the Ne IX resonance line and the dielectronic satellites using recent theoretical calculations. The temperature values ranged from 210 eV to 340 eV during the time of occurrence of these satellites. The temperature measured at 1.0 μs by laser scattering for a similar plasma condition was in close agreement with that obtained by the resonance line/satellite ratio. This lends confidence to use of the satellite technique for temperature measurements in other plasmas

  7. Applications of Geostationary Satellite Data to Aviation

    Science.gov (United States)

    Ellrod, Gary P.; Pryor, Kenneth

    2018-03-01

    Weather is by far the most important factor in air traffic delays in the United States' National Airspace System (NAS) according to the Federal Aviation Administration (FAA). Geostationary satellites have been an effective tool for the monitoring of meteorological conditions that affect aviation operations since the launch of the first Synchronous Meteorological Satellite (SMS) in the United States in 1974. This paper will review the global use of geostationary satellites in support of aviation weather since their inception, with an emphasis on the latest generation of satellites, such as Geostationary Operational Environmental Satellite (GOES)-R (16) with its Advanced Baseline Imager (ABI) and Geostationary Lightning Mapper (GLM). Specific applications discussed in this paper include monitoring of convective storms and their associated hazards, fog and low stratus, turbulence, volcanic hazards, and aircraft icing.

  8. Future Satellite Gravimetry and Earth Dynamics

    CERN Document Server

    Flury, Jakob

    2005-01-01

    Currently, a first generation of dedicated satellite missions for the precise mapping of the Earth’s gravity field is in orbit (CHAMP, GRACE, and soon GOCE). The gravity data from these satellite missions provide us with very new information on the dynamics of planet Earth. In particular, on the mass distribution in the Earth’s interior, the entire water cycle (ocean circulation, ice mass balance, continental water masses, and atmosphere), and on changes in the mass distribution. The results are fascinating, but still rough with respect to spatial and temporal resolution. Technical progress in satellite-to-satellite tracking and in gravity gradiometry will allow more detailed results in the future. In this special issue, Earth scientists develop visions of future applications based on follow-on high-precision satellite gravimetry missions.

  9. Orbital and Collisional Evolution of the Irregular Satellites

    Science.gov (United States)

    Nesvorný, David; Alvarellos, Jose L. A.; Dones, Luke; Levison, Harold F.

    2003-07-01

    instabilities operating on longer time spans. The average orbits calculated from this experiment were then used to probe the collisional evolution of the irregular satellite systems. We found that (1) the large irregular moons must have collisionally eliminated many small irregular moons, thus shaping their population to the currently observed structures; (2) some dynamical families of satellites could have been formed by catastrophic collisions among the irregular moons; and (3) Phoebe's surface must have been heavily cratered by impacts from an extinct population of Saturnian irregular moons, much larger than the present one. We therefore suggest that the Cassini imaging of Phoebe in 2004 can be used to determine the primordial population of small irregular moons of Saturn. In such a case, we will also better understand the overall efficiency of the formation process of the irregular satellites and the physical conditions that existed during planetary formation. We discovered two dynamical families of tightly clustered orbits within the Jovian retrograde group. We believe that these two clusters may be the remnants of two collisionally disrupted bodies. We found that the entire Jovian retrograde group and the Saturnian inclination groups were not produced by single breakups, because the ejection velocities derived from the orbital structures of these groups greatly exceed values calculated by modern numerical models of collisional breakups. Taken together, the evidence presented here suggests that many properties of the irregular moons previously assigned to their formation process may have resulted from their later dynamical and collisional evolution. Finally, we have found that several irregular moons, namely, Pasiphae, Sinope, S/2001 J10, S/2000 S5, S/2000 S6, and S/2000 S3, have orbits characterized by secular resonances. The orbits of some of these moons apparently evolved by some slow dissipative process in the past and became captured in tiny resonant volumes.

  10. Integrated Stewardship of NASA Satellite and Field Campaign Data

    Science.gov (United States)

    Hausman, J.; Tsontos, V. M.; Hardman, S. H.

    2016-02-01

    The Physical Oceanography Distributed Active Archive Center (PO.DAAC) is NASA's archive, steward and distributor for physical oceanographic satellite data. Those data are typically organized along the lines of single parameters, such as Sea Surface Temperature, Ocean Winds, Salinity, etc. However there is a need supplement satellite data with in situ and various other remote sensing data to provide higher spatial and temporal sampling and information on physical processes that the satellites are not capable of measuring. This presentation will discuss how PO.DAAC is creating a stewardship and distribution plan that will accommodate satellite, in situ and other remote sensing data that can be used to solve a more integrated approach to data access and utilization along thematic lines in support of science and applications, specifically those posed by Salinity Processes in the Upper Ocean Regional Study (SPURS) and Oceans Melting Greenland (OMG) projects. SPURS used shipboard data, moorings and in situ instruments to investigate changes in salinity and how that information can be used in explaining the water cycle. OMG is studying ice melt in Greenland and how it contributes to changes in sea level through shipboard measurements, airborne and a variety of in situ instruments. PO.DAAC plans on adapting to stewarding and distributing these varieties of data through applications of file format and metadata standards (so data are discoverable and interoperable), extend the internal data system (to allow for better archiving, collection generation and querying of in situ and airborne data) and integration into tools (visualization and data access). We are also working on Virtual Collections with ESDWG, which could provide access to relevant data across DAACs/Agencies along thematic lines. These improvements will improve long-term data management and make it easier for users of various background, regardless if remote sensing or in situ, to discover and use the data.

  11. Formation of Ice Giant Satellites During Thommes Model Mirgration

    Science.gov (United States)

    Fuse, Christopher; Spiegelberg, Josephine

    2018-01-01

    Inconsistencies between ice giant planet characteristics and classic planet formation theories have led to a re-evaluation of the formation of the outer Solar system. Thommes model migration delivers proto-Uranus and Neptune from orbits interior to Saturn to their current locations. The Thommes model has also been able to reproduce the large Galilean and Saturnian moons via interactions between the proto-ice giants and the gas giant moon disks.As part of a series of investigations examining the effects of Thommes model migration on the formation of moons, N-body simulations of the formation of the Uranian and Neptunian satellite systems were performed. Previous research has yielded conflicting results as to whether satellite systems are stable during planetary migration. Some studies, such as Beaugé (2002) concluded that the system was not stable over the proposed duration of migration. Conversely, Fuse and Neville (2011) and Yokoyama et al. (2011) found that moons were retained, though the nature of the resulting system was heavily influenced by interactions with planetesimals and other large objects. The results of the current study indicate that in situ simulations of the Uranus and Neptune systems can produce stable moons. Whether with current orbital parameters or located at pre-migration, inner Solar system semi-major axes, the simulations end with 5.8 ± 0.15 or 5.9 ± 0.7 regular satellites around Uranus and Neptune, respectively. Preliminary simulations of a proto-moon disk around a single planet migrating via the Thommes model have failed to retain moons. Furthermore, simulations of ejection of the current Uranian satellite system retained at most one moon. Thus, for the Thommes model to be valid, it is likely that moon formation did not begin until after migration ended. Future work will examine the formation of gas and ice giant moons through other migration theories, such as the Nice model (Tsiganis et al. 2006).

  12. Regulation of satellite cell function in sarcopenia

    Directory of Open Access Journals (Sweden)

    Stephen E Alway

    2014-09-01

    Full Text Available The mechanisms contributing to sarcopenia include reduced satellite cell (myogenic stem cell function that is impacted by the environment (niche of these cells. Satellite cell function is affected by oxidative stress, which is elevated in aged muscles, and this along with changes in largely unknown systemic factors, likely contribute to the manner in which satellite cells respond to stressors such as exercise, disuse or rehabilitation in sarcopenic muscles. Nutritional intervention provides one therapeutic strategy to improve the satellite cell niche and systemic factors, with the goal of improving satellite cell function in aging muscles. Although many elderly persons consume various nutraceuticals with the hope of improving health, most of these compounds have not been thoroughly tested, and the impacts that they might have on sarcopenia, and satellite cell function are not clear. This review discusses data pertaining to the satellite cell responses and function in aging skeletal muscle, and the impact that three compounds: resveratrol, green tea catechins and β-Hydroxy-β-methylbutyrate have on regulating satellite cell function and therefore contributing to reducing sarcopenia or improving muscle mass after disuse in aging. The data suggest that these nutraceutical compounds improve satellite cell function during rehabilitative loading in animal models of aging after disuse (i.e., muscle regeneration. While these compounds have not been rigorously tested in humans, the data from animal models of aging provide a strong basis for conducting additional focused work to determine if these or other nutraceuticals can offset the muscle losses, or improve regeneration in sarcopenic muscles of older humans via improving satellite cell function.

  13. Regulation of Satellite Cell Function in Sarcopenia

    Science.gov (United States)

    Alway, Stephen E.; Myers, Matthew J.; Mohamed, Junaith S.

    2014-01-01

    The mechanisms contributing to sarcopenia include reduced satellite cell (myogenic stem cell) function that is impacted by the environment (niche) of these cells. Satellite cell function is affected by oxidative stress, which is elevated in aged muscles, and this along with changes in largely unknown systemic factors, likely contribute to the manner in which satellite cells respond to stressors such as exercise, disuse, or rehabilitation in sarcopenic muscles. Nutritional intervention provides one therapeutic strategy to improve the satellite cell niche and systemic factors, with the goal of improving satellite cell function in aging muscles. Although many elderly persons consume various nutraceuticals with the hope of improving health, most of these compounds have not been thoroughly tested, and the impacts that they might have on sarcopenia and satellite cell function are not clear. This review discusses data pertaining to the satellite cell responses and function in aging skeletal muscle, and the impact that three compounds: resveratrol, green tea catechins, and β-Hydroxy-β-methylbutyrate have on regulating satellite cell function and therefore contributing to reducing sarcopenia or improving muscle mass after disuse in aging. The data suggest that these nutraceutical compounds improve satellite cell function during rehabilitative loading in animal models of aging after disuse (i.e., muscle regeneration). While these compounds have not been rigorously tested in humans, the data from animal models of aging provide a strong basis for conducting additional focused work to determine if these or other nutraceuticals can offset the muscle losses, or improve regeneration in sarcopenic muscles of older humans via improving satellite cell function. PMID:25295003

  14. Changing inclination of earth satellites using the gravity of the moon

    Directory of Open Access Journals (Sweden)

    Karla de Souza Torres

    2006-01-01

    Full Text Available We analyze the problem of the orbital control of an Earth's satellite using the gravity of the Moon. The main objective is to study a technique to decrease the fuel consumption of a plane change maneuver to be performed in a satellite that is in orbit around the Earth. The main idea of this approach is to send the satellite to the Moon using a single-impulsive maneuver, use the gravity field of the Moon to make the desired plane change of the trajectory, and then return the satellite to its nominal semimajor axis and eccentricity using a bi-impulsive Hohmann-type maneuver. The satellite is assumed to start in a Keplerian orbit in the plane of the lunar orbit around the Earth and the goal is to put it in a similar orbit that differs from the initial orbit only by the inclination. A description of the close-approach maneuver is made in the three-dimensional space. Analytical equations based on the patched conics approach are used to calculate the variation in velocity, angular momentum, energy, and inclination of the satellite. Then, several simulations are made to evaluate the savings involved. The time required by those transfers is also calculated and shown.

  15. Satellite Eye for Galathea 3. Annual report 2006

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay; Sørensen, Peter; Pedersen, Leif Toudal

    The Satellite Eye for Galathea 3 project is collecting satellite images from many satellites and, in particular, from the European ENVISAT satellite along the Galathea 3 global route. The expedition takes place from 11 August 2006 to 27 April 2007. Prior to the expedition several satellite images...... Vædderen, pupils in the classrooms and the public at any moment can take a look at the conditions seen from the eyes of the Earth observing satellites....

  16. Validation of double Langmuir probe in-orbit performance onboard a nano-satellite

    Science.gov (United States)

    Tejumola, Taiwo Raphael; Zarate Segura, Guillermo Wenceslao; Kim, Sangkyun; Khan, Arifur; Cho, Mengu

    2018-03-01

    Many plasma measurement systems have been proposed and used onboard different satellites to characterize space plasma. Most of these systems employed the technique of Langmuir probes either using the single or double probes methods. Recent growth of lean satellites has positioned it on advantage to be used for space science missions using Langmuir probes because of its simplicity and convenience. However, single Langmuir probes are not appropriate to be used on lean satellites because of their limited conducting area which leads to spacecraft charging and drift of the instrument's electrical ground during measurement. Double Langmuir probes technique can overcome this limitation, as a measurement reference in relation to the spacecraft is not required. A double Langmuir probe measurement system was designed and developed at Kyushu Institute of Technology for HORYU-IV satellite, which is a 10 kg, 30 cm cubic class lean satellite launched into Low Earth Orbit on 17th February 2016. This paper presents the on-orbit performance and validation of the double Langmuir probe measurement using actual on-orbit measured data and computer simulations.

  17. a Thtee-Dimensional Variational Assimilation Scheme for Satellite Aod

    Science.gov (United States)

    Liang, Y.; Zang, Z.; You, W.

    2018-04-01

    A three-dimensional variational data assimilation scheme is designed for satellite AOD based on the IMPROVE (Interagency Monitoring of Protected Visual Environments) equation. The observation operator that simulates AOD from the control variables is established by the IMPROVE equation. All of the 16 control variables in the assimilation scheme are the mass concentrations of aerosol species from the Model for Simulation Aerosol Interactions and Chemistry scheme, so as to take advantage of this scheme in providing comprehensive analyses of species concentrations and size distributions as well as be calculating efficiently. The assimilation scheme can save computational resources as the IMPROVE equation is a quadratic equation. A single-point observation experiment shows that the information from the single-point AOD is effectively spread horizontally and vertically.

  18. Grand Challenges in Space Technology: Distributed Satellite Systems

    National Research Council Canada - National Science Library

    Miller, David

    2001-01-01

    The MITIAFRL Distributed Satellite Systems program examines the motivation, analysis and development of technology associated with the distribution of assets and functionality over a number of cooperating satellites...

  19. DEPRON dosimeter for ``Lomonosov'' satellite

    Science.gov (United States)

    Brilkov, Ivan; Vedenkin, Nikolay; Panasyuk, Mikhail; Amelyushkin, Aleksandr; Petrov, Vasily; Nechayev, Oleg; Benghin, Victor

    It is commonly known, that cosmic radiation generates negative impact on the human body during space flight. The structure of the radiation fields in the near-Earth space was studied during intensive research of recent decades. Huge number of dosimetry studies was conducted on manned and unmanned space vehicles in order to solve the problem of radiation safety humans during space flights. It should be noted that most of the measurements was made onboard the spacecrafts, flying along the orbits with inclination of up to 51.6 degrees. Due to the prospect of manned missions at the orbits with larger inclination it seems advisable to conduct preliminary detailed dosimetry measurements at high-altitude orbit, for which the "Lomonosov" satellite provides good opportunities. We chose a method of cosmic radiation dosimetry based on semiconductor detectors. Proposed in the late 70's this method is widely used onboard spacecraft, including full-time radiation monitoring onboard the ISS. Recently it has been improved, providing an opportunity to register not only the absorbed dose of charged particles radiation, but also range of their ionization losses. It allowed assessment of equivalent dose. Appropriate procedure based on using of a telescope consisting of two semiconductor detectors provided a basis of the developed unit. It should be noted that not only the charged particles contribute significantly in the equivalent dose, but also neutrons do. Semiconductor detectors have low sensitivity to neutron radiation and are not sufficient for detecting the expected flux of neutrons. It was therefore decided to add thermal neutrons counter to the developed device in order to provide an opportunity of estimation of neutron flux variations along the satellite trajectory. A gas-discharge counter SI-13N, operated in a mode of corona discharge was chosen as a neutron detector. This method of neutron detection is well-proven and used many times in SINP MSU experiments. Thus, the

  20. PRMT7 Preserves Satellite Cell Regenerative Capacity

    Directory of Open Access Journals (Sweden)

    Roméo Sébastien Blanc

    2016-02-01

    Full Text Available Regeneration of skeletal muscle requires the continued presence of quiescent muscle stem cells (satellite cells, which become activated in response to injury. Here, we report that whole-body protein arginine methyltransferase PRMT7−/− adult mice and mice conditionally lacking PRMT7 in satellite cells using Pax7-CreERT2 both display a significant reduction in satellite cell function, leading to defects in regenerative capacity upon muscle injury. We show that PRMT7 is preferentially expressed in activated satellite cells and, interestingly, PRMT7-deficient satellite cells undergo cell-cycle arrest and premature cellular senescence. These defects underlie poor satellite cell stem cell capacity to regenerate muscle and self-renew after injury. PRMT7-deficient satellite cells express elevated levels of the CDK inhibitor p21CIP1 and low levels of its repressor, DNMT3b. Restoration of DNMT3b in PRMT7-deficient cells rescues PRMT7-mediated senescence. Our findings define PRMT7 as a regulator of the DNMT3b/p21 axis required to maintain muscle stem cell regenerative capacity.

  1. Satellite cells in human skeletal muscle plasticity

    Directory of Open Access Journals (Sweden)

    Tim eSnijders

    2015-10-01

    Full Text Available Skeletal muscle satellite cells are considered to play a crucial role in muscle fiber maintenance, repair and remodelling. Our knowledge of the role of satellite cells in muscle fiber adaptation has traditionally relied on in vitro cell and in vivo animal models. Over the past decade, a genuine effort has been made to translate these results to humans under physiological conditions. Findings from in vivo human studies suggest that satellite cells play a key role in skeletal muscle fiber repair/remodelling in response to exercise. Mounting evidence indicates that aging has a profound impact on the regulation of satellite cells in human skeletal muscle. Yet, the precise role of satellite cells in the development of muscle fiber atrophy with age remains unresolved. This review seeks to integrate recent results from in vivo human studies on satellite cell function in muscle fiber repair/remodelling in the wider context of satellite cell biology whose literature is largely based on animal and cell models.

  2. Estimates of the Spectral Aerosol Single Sea Scattering Albedo and Aerosol Radiative Effects during SAFARI 2000

    Science.gov (United States)

    Bergstrom, Robert W.; Pilewskie, Peter; Schmid, Beat; Russell, Philip B.

    2003-01-01

    Using measurements of the spectral solar radiative flux and optical depth for 2 days (24 August and 6 September 2000) during the SAFARI 2000 intensive field experiment and a detailed radiative transfer model, we estimate the spectral single scattering albedo of the aerosol layer. The single scattering albedo is similar on the 2 days even though the optical depth for the aerosol layer was quite different. The aerosol single scattering albedo was between 0.85 and 0.90 at 350 nm, decreasing to 0.6 in the near infrared. The magnitude and decrease with wavelength of the single scattering albedo are consistent with the absorption properties of small black carbon particles. We estimate the uncertainty in the single scattering albedo due to the uncertainty in the measured fractional absorption and optical depths. The uncertainty in the single scattering albedo is significantly less on the high-optical-depth day (6 September) than on the low-optical-depth day (24 August). On the high-optical-depth day, the uncertainty in the single scattering albedo is 0.02 in the midvisible whereas on the low-optical-depth day the uncertainty is 0.08 in the midvisible. On both days, the uncertainty becomes larger in the near infrared. We compute the radiative effect of the aerosol by comparing calculations with and without the aerosol. The effect at the top of the atmosphere (TOA) is to cool the atmosphere by 13 W/sq m on 24 August and 17 W/sq m on 6 September. The effect on the downward flux at the surface is a reduction of 57 W/sq m on 24 August and 200 W/sq m on 6 September. The aerosol effect on the downward flux at the surface is in good agreement with the results reported from the Indian Ocean Experiment (INDOEX).

  3. Protected transitional solution to transformational satellite communications

    Science.gov (United States)

    Brand, Jerry C.

    2005-06-01

    As the Warfighter progresses into the next generation battlefield, transformational communications become evident as an enabling technology. Satellite communications become even more vital as the battles range over greater non-contiguous spaces. While current satellite communications provide suitable beyond line-of-sight communications and the Transformational Communications Architecture (TCA) sets the stage for sound information exchange, a realizable transition must occur to ensure successful succession to this higher level. This paper addresses the need for a planned escalation to the next generation satellite communications architecture and offers near-term alternatives. Commercial satellite systems continue to enable the Warfighter to reach back to needed information resources, providing a large majority of available bandwidth. Four areas of concentration for transition include encrypted Telemetry, Tracking and Control (or Command) (TT&C), encrypted and covered data, satellite attack detection and protection, and operational mobility. Solution methodologies include directly embedding COMSEC devices in the satellites and terminals, and supplementing existing terminals with suitable equipment and software. Future satellites planned for near-term launches can be adapted to include commercial grade and higher-level secure equipment. Alternately, the expected use of programmable modems (Software Defined Radios (SDR)) enables incorporation of powerful cipher methods approaching military standards as well as waveforms suitable for on-the-move operation. Minimal equipment and software additions on the satellites can provide reasonable attack detection and protection methods in concert with the planned satellite usage. Network management suite modifications enable cohesive incorporation of these protection schemes. Such transitional ideas offer a smooth and planned transition as the TCA takes life.

  4. Satellite ATM Networks: Architectures and Guidelines Developed

    Science.gov (United States)

    vonDeak, Thomas C.; Yegendu, Ferit

    1999-01-01

    An important element of satellite-supported asynchronous transfer mode (ATM) networking will involve support for the routing and rerouting of active connections. Work published under the auspices of the Telecommunications Industry Association (http://www.tiaonline.org), describes basic architectures and routing protocol issues for satellite ATM (SATATM) networks. The architectures and issues identified will serve as a basis for further development of technical specifications for these SATATM networks. Three ATM network architectures for bent pipe satellites and three ATM network architectures for satellites with onboard ATM switches were developed. The architectures differ from one another in terms of required level of mobility, supported data rates, supported terrestrial interfaces, and onboard processing and switching requirements. The documentation addresses low-, middle-, and geosynchronous-Earth-orbit satellite configurations. The satellite environment may require real-time routing to support the mobility of end devices and nodes of the ATM network itself. This requires the network to be able to reroute active circuits in real time. In addition to supporting mobility, rerouting can also be used to (1) optimize network routing, (2) respond to changing quality-of-service requirements, and (3) provide a fault tolerance mechanism. Traffic management and control functions are necessary in ATM to ensure that the quality-of-service requirements associated with each connection are not violated and also to provide flow and congestion control functions. Functions related to traffic management were identified and described. Most of these traffic management functions will be supported by on-ground ATM switches, but in a hybrid terrestrial-satellite ATM network, some of the traffic management functions may have to be supported by the onboard satellite ATM switch. Future work is planned to examine the tradeoffs of placing traffic management functions onboard a satellite as

  5. Satellite Application for Disaster Management Information Systems

    Science.gov (United States)

    Okpanachi, George

    Abstract Satellites are becoming increasingly vital to modern day disaster management activities. Earth observation (EO) satellites provide images at various wavelengths that assist rapid-mapping in all phases of the disaster management cycle: mitigation of potential risks in a given area, preparedness for eventual disasters, immediate response to a disaster event, and the recovery/reconstruction efforts follo wing it. Global navigation satellite systems (GNSS) such as the Global Positioning System (GPS) assist all the phases by providing precise location and navigation data, helping manage land and infrastructures, and aiding rescue crews coordinate their search efforts. Effective disaster management is a complex problem, because it involves many parameters, which are usually not easy to measure and even identify: Analysis of current situation, planning, optimum resource management, coordination, controlling and monitoring current activities and making quick and correct decisions are only some of these parameters, whose complete list is very long. Disaster management information systems (DMIS) assist disaster management to analyse the situation better, make decisions and suggest further actions following the emergency plans. This requires not only fast and thorough processing and optimization abilities, but also real-time data provided to the DMIS. The need of DMIS for disaster’s real-time data can be satisfied by small satellites data utilization. Small satellites can provide up-to-data, plus a better media to transfer data. This paper suggests a rationale and a framework for utilization of small Satellite data by DMIS. DMIS should be used ‘’before’’, ‘’during’’ and ‘’after’’ the disasters. Data provided by the Small Satellites are almost crucial in any period of the disasters, because early warning can save lives, and satellite data may help to identify disasters before they occur. The paper also presents’ ‘when’’,

  6. Interfering Satellite RNAs of Bamboo mosaic virus

    Directory of Open Access Journals (Sweden)

    Kuan-Yu Lin

    2017-05-01

    Full Text Available Satellite RNAs (satRNAs are sub-viral agents that may interact with their cognate helper virus (HV and host plant synergistically and/or antagonistically. SatRNAs totally depend on the HV for replication, so satRNAs and HV usually evolve similar secondary or tertiary RNA structures that are recognized by a replication complex, although satRNAs and HV do not share an appreciable sequence homology. The satRNAs of Bamboo mosaic virus (satBaMV, the only satRNAs of the genus Potexvirus, have become one of the models of how satRNAs can modulate HV replication and virus-induced symptoms. In this review, we summarize the molecular mechanisms underlying the interaction of interfering satBaMV and BaMV. Like other satRNAs, satBaMV mimics the secondary structures of 5′- and 3′-untranslated regions (UTRs of BaMV as a molecular pretender. However, a conserved apical hairpin stem loop (AHSL in the 5′-UTR of satBaMV was found as the key determinant for downregulating BaMV replication. In particular, two unique nucleotides (C60 and C83 in the AHSL of satBaMVs determine the satBaMV interference ability by competing for the replication machinery. Thus, transgenic plants expressing interfering satBaMV could confer resistance to BaMV, and interfering satBaMV could be used as biological-control agent. Unlike two major anti-viral mechanisms, RNA silencing and salicylic acid-mediated immunity, our findings in plants by in vivo competition assay and RNA deep sequencing suggested replication competition is involved in this transgenic satBaMV-mediated BaMV interference. We propose how a single nucleotide of satBaMV can make a great change in BaMV pathogenicity and the underlying mechanism.

  7. Multi-Satellite MIMO Communications at Ku-Band and Above: Investigations on Spatial Multiplexing for Capacity Improvement and Selection Diversity for Interference Mitigation

    Directory of Open Access Journals (Sweden)

    Liolis Konstantinos P

    2007-01-01

    Full Text Available This paper investigates the applicability of multiple-input multiple-output (MIMO technology to satellite communications at the Ku-band and above. After introducing the possible diversity sources to form a MIMO matrix channel in a satellite environment, particular emphasis is put on satellite diversity. Two specific different topics from the field of MIMO technology applications to satellite communications at these frequencies are further analyzed: (i capacity improvement achieved by MIMO spatial multiplexing systems and (ii interference mitigation achieved by MIMO diversity systems employing receive antenna selection. In the first case, a single-user capacity analysis of a satellite MIMO spatial multiplexing system is presented and a useful analytical closed form expression is derived for the outage capacity achieved. In the second case, a satellite MIMO diversity system with receive antenna selection is considered, adjacent satellite cochannel interference on its forward link is studied and an analytical model predicting the interference mitigation achieved is presented. In both cases, an appropriate physical MIMO channel model is assumed which takes into account the propagation phenomena related to the frequencies of interest, such as clear line-of-sight operation, high antenna directivity, the effect of rain fading, and the slant path lengths difference. Useful numerical results obtained through the analytical expressions derived are presented to compare the performance of multi-satellite MIMO systems to relevant single-input single-output (SISO ones.

  8. Technical developments in international satellite business services

    Science.gov (United States)

    Tan, P. P.

    At the conception of International Satellite Business Services (ISBS), it was a primary objective to provide flexibility for accommodating a variety of service requirements which might be established by mutual agreement between users. The design guidelines are to ensure that the space segment is efficiently utilized, while other satellite services are protected from interference. Other considerations are related to an acceptable earth segment cost, maximum connectivity in worldwide services, the capability of growth and a reasonably smooth transition into future systems, and the maintenance of high performance objectives. Attention is given to a system overview, the characteristics of satellites for ISBS, and technological developments with some application possibilities for ISBS.

  9. Solar array experiments on the Sphinx satellite

    Science.gov (United States)

    Stevens, N. J.

    1973-01-01

    The Space Plasma, High Voltage Interaction Experiment (SPHINX) is the name given to an auxiliary payload satellite scheduled to be launched in January 1974. The principal experiments carried on this satellite are specifically designed to obtain the engineering data on the interaction of high voltage systems with the space plasma. The classes of experiments are solar array segments, insulators, insulators with pin holes and conductors. The satellite is also carrying experiments to obtain flight data on three new solar array configurations; the edge illuminated-multijunction cells, the Teflon encased cells and the violet cells.

  10. Small satellites and space debris issues

    Science.gov (United States)

    Yakovlev, M.; Kulik, S.; Agapov, V.

    2001-10-01

    The objective of this report is the analysis of the tendencies in designing of small satellites (SS) and the effect of small satellites on space debris population. It is shown that SS to include nano- and pico-satellites should be considered as a particularly dangerous source of space debris when elaborating international standards and legal documents concerning the space debris problem, in particular "International Space Debris Mitigation Standard". These issues are in accordance with the IADC goals in its main activity areas and should be carefully considered within the IADC framework.

  11. Influence of space radiation on satellite magnetics

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, M K [Vikram Sarabhai Space Centre, Trivandrum (India)

    1978-12-01

    The magnetic circuits and devices used in space-borne systems such as satellites are naturally exposed to space environments having among others, hazardous radiations. Such radiations, in turn, may be of solar, cosmic or nuclear origin depending upon the altitude as well as the propulsion/power systems involving mini atomic reactors when utilised. The influence of such radiations on the magnetic components of the satellite have been analysed revealing the critical hazards in the latter circuits system. Remedial measures by appropriate shielding, etc. necessary for maintaining optimum performance of the satellite have been discussed.

  12. On-board processing for telecommunications satellites

    Science.gov (United States)

    Nuspl, P. P.; Dong, G.

    1991-01-01

    In this decade, communications satellite systems will probably face dramatic challenges from alternative transmission means. To balance and overcome such competition, and to prepare for new requirements, INTELSAT has developed several on-board processing techniques, including Satellite-Switched TDMA (SS-TDMA), Satellite-Switched FDMA (SS-FDMA), several Modulators/Demodulators (Modem), a Multicarrier Multiplexer and Demodulator MCDD), an International Business Service (IBS)/Intermediate Data Rate (IDR) BaseBand Processor (BBP), etc. Some proof-of-concept hardware and software were developed, and tested recently in the INTELSAT Technical Laboratories. These techniques and some test results are discussed.

  13. Egypt satellite images for land surface characterization

    DEFF Research Database (Denmark)

    Hasager, Charlotte Bay

    images used for mapping the vegetation cover types and other land cover types in Egypt. The mapping ranges from 1 km resolution to 30 m resolution. The aim is to provide satellite image mapping with land surface characteristics relevant for roughness mapping.......Satellite images provide information on the land surface properties. From optical remote sensing images in the blue, green, red and near-infrared part of the electromagnetic spectrum it is possible to identify a large number of surface features. The report briefly describes different satellite...

  14. ARTES: the future of satellite telecommunication

    Science.gov (United States)

    González-Blázquez, Angel; Detain, Dominique

    2005-08-01

    Throughout its 30-year existence, ESA has played a key role by providing telecommunications infrastructures that have allowed the in-orbit validation, qualification and demonstration of equipment, technology and services. In the past, this has been achieved through the provision of dedicated satellites like OTS, Marecs, Olympus and Artemis, as well as by the implementation of piggy-back payloads on other ESA or commercial satellites. Today, due to the importance of satellite telecommunications, ESA continues to support this sector mainly through its ARTES - Advanced Research in Telecommunications - Programme.

  15. Satellite Communication and Long Distance Education

    Directory of Open Access Journals (Sweden)

    Hafied Cangara

    2016-02-01

    Full Text Available Since Indonesia introduced communication satellite for telecommunication network, the satellite has brought a number of advantages for national development in various areas, such as telephone network, mass media development, business, education, politics, security and national defence as well as regional and international cooperation. In education, satellite communication could be used for long-distance learning as implemented by 13 state universities in eastern parts of Indonesia. It is also possible to develop the Open University System in teaching and learning process, particularly since the internet technology has been intensively used

  16. Satellite Attitude Control Using Only Electromagnetic Actuation

    DEFF Research Database (Denmark)

    Wisniewski, Rafal

    when a satellite is on a throughout this thesis. Confined computer capacity and a limit on electrical power supply were separate obstacles.They demanded computational simplicity and power optimality from the attitude control system. The design of quasi optimal controllers for a real-time implementation...... to provide four stable equilibria, one of which was the desired orientation. It was explained how the equilibria depended on the ratio of the satellite's moments of inertia. It was further investigated how to control the attitude, such that the satellite was globally asymptotically stable in the desired...

  17. Deep space optical communication via relay satellite

    Science.gov (United States)

    Dolinar, S.; Vilnrotter, V.; Gagliardi, R.

    1981-01-01

    The application of optical communications for a deep space link via an earth-orbiting relay satellite is discussed. The system uses optical frequencies for the free-space channel and RF links for atmospheric transmission. The relay satellite is in geostationary orbit and contains the optics necessary for data processing and formatting. It returns the data to earth through the RF terrestrial link and also transmits an optical beacon to the satellite for spacecraft return pointing and for the alignment of the transmitting optics. Future work will turn to modulation and coding, pointing and tracking, and optical-RF interfacing.

  18. Satellite Remote Sensing: Aerosol Measurements

    Science.gov (United States)

    Kahn, Ralph A.

    2013-01-01

    Aerosols are solid or liquid particles suspended in the air, and those observed by satellite remote sensing are typically between about 0.05 and 10 microns in size. (Note that in traditional aerosol science, the term "aerosol" refers to both the particles and the medium in which they reside, whereas for remote sensing, the term commonly refers to the particles only. In this article, we adopt the remote-sensing definition.) They originate from a great diversity of sources, such as wildfires, volcanoes, soils and desert sands, breaking waves, natural biological activity, agricultural burning, cement production, and fossil fuel combustion. They typically remain in the atmosphere from several days to a week or more, and some travel great distances before returning to Earth's surface via gravitational settling or washout by precipitation. Many aerosol sources exhibit strong seasonal variability, and most experience inter-annual fluctuations. As such, the frequent, global coverage that space-based aerosol remote-sensing instruments can provide is making increasingly important contributions to regional and larger-scale aerosol studies.

  19. Cosmology with the Planck Satellite

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    Sketched out in 1992, selected by ESA in 1996, and launched in 2009, the Planck satellite was shut off in 2013, after a measuring mission that exceeded all expectations. The Planck collaboration delivered a first set of cosmological data and results in March 21st 2013, and the full set in February 2015. Part of the data delivery is a "definitive" map of the anisotropies of the Cosmic Microwave Background (CMB), its angular power spectrum together with their full statistical characterisation. The 2015 delivery also includes pioneering polarisation data. The temperature anisotropy map displays minuscule variations as a function of the observing direction, of rms ~100microK, of the fossil radiation around its mean temperature of 2.725K. Other maps reveal the CMB polarisation. The anisotropies are the imprint of the primordial fluctuations which initiated the growth of the large scale structures of the Universe, as transformed by their evolution, in particular during the first 370 000 years, as well as finer e...

  20. Odyssey, an optimized personal communications satellite system

    Science.gov (United States)

    Rusch, Roger J.

    Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry is developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, "bent pipe" transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 Watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. There are three orbit planes inclined at 55° to the equatorial plane

  1. Space Network IP Services (SNIS): An Architecture for Supporting Low Earth Orbiting IP Satellite Missions

    Science.gov (United States)

    Israel, David J.

    2005-01-01

    The NASA Space Network (SN) supports a variety of missions using the Tracking and Data Relay Satellite System (TDRSS), which includes ground stations in White Sands, New Mexico and Guam. A Space Network IP Services (SNIS) architecture is being developed to support future users with requirements for end-to-end Internet Protocol (IP) communications. This architecture will support all IP protocols, including Mobile IP, over TDRSS Single Access, Multiple Access, and Demand Access Radio Frequency (RF) links. This paper will describe this architecture and how it can enable Low Earth Orbiting IP satellite missions.

  2. The NASA Earth Science Program and Small Satellites

    Science.gov (United States)

    Neeck, Steven P.

    2015-01-01

    Earth's changing environment impacts every aspect of life on our planet and climate change has profound implications on society. Studying Earth as a single complex system is essential to understanding the causes and consequences of climate change and other global environmental concerns. NASA's Earth Science Division (ESD) shapes an interdisciplinary view of Earth, exploring interactions among the atmosphere, oceans, ice sheets, land surface interior, and life itself. This enables scientists to measure global and climate changes and to inform decisions by Government, other organizations, and people in the United States and around the world. The data collected and results generated are accessible to other agencies and organizations to improve the products and services they provide, including air quality indices, disaster prediction and response, agricultural yield projections, and aviation safety. ESD's Flight Program provides the spacebased observing systems and supporting infrastructure for mission operations and scientific data processing and distribution that support NASA's Earth science research and modeling activities. The Flight Program currently has 21 operating Earth observing space missions, including the recently launched Global Precipitation Measurement (GPM) mission, the Orbiting Carbon Observatory-2 (OCO-2), the Soil Moisture Active Passive (SMAP) mission, and the International Space Station (ISS) RapidSCAT and Cloud-Aerosol Transport System (CATS) instruments. The ESD has 22 more missions and instruments planned for launch over the next decade. These include first and second tier missions from the 2007 Earth Science Decadal Survey, Climate Continuity missions to assure availability of key climate data sets, and small-sized competitively selected orbital missions and instrument missions of opportunity belonging to the Earth Venture (EV) Program. Small satellites (500 kg or less) are critical contributors to these current and future satellite missions

  3. Fuzzy Logic Controller for Small Satellites Navigation

    National Research Council Canada - National Science Library

    Della Pietra, G; Falzini, S; Colzi, E; Crisconio, M

    2005-01-01

    .... The navigator aims at operating satellites in orbit with a minimum ground support and very good performances, by the adoption of innovative technologies, such as attitude observation GPS, attitude...

  4. Flight Demonstration of Novel Atmospheric Satellite Concept

    Data.gov (United States)

    National Aeronautics and Space Administration — The Dual-Aircraft Platform (DAP) is a novel concept for achieving a low-cost atmospheric satellite in the lower stratosphere which utilizes a combination of wind and...

  5. National Satellite Land Remote Sensing Data Archive

    Science.gov (United States)

    Faundeen, John L.; Kelly, Francis P.; Holm, Thomas M.; Nolt, Jenna E.

    2013-01-01

    The National Satellite Land Remote Sensing Data Archive (NSLRSDA) resides at the U.S. Geological Survey's (USGS) Earth Resources Observation and Science (EROS) Center. Through the Land Remote Sensing Policy Act of 1992, the U.S. Congress directed the Department of the Interior (DOI) to establish a permanent Government archive containing satellite remote sensing data of the Earth's land surface and to make this data easily accessible and readily available. This unique DOI/USGS archive provides a comprehensive, permanent, and impartial observational record of the planet's land surface obtained throughout more than five decades of satellite remote sensing. Satellite-derived data and information products are primary sources used to detect and understand changes such as deforestation, desertification, agricultural crop vigor, water quality, invasive plant species, and certain natural hazards such as flood extent and wildfire scars.

  6. On possible life on Jupiter's satellite Io

    Science.gov (United States)

    Vidmachenko, A. P.

    2018-05-01

    Some of the satellites of Jupiter may well be suitable both for mastering, and for finding possible traces of life there. Among them such satellite like Io - nearest Galilean satellite of Jupiter, and one of the most volcanically active bodies in the solar system. Warming of the mantle is caused by a powerful tidal force from the side of Jupiter. This leads to the heating of some parts of the mantle to a temperature above 1800 K, with an average surface temperature of about 140 K. But under its surface can be safe and even comfortable shelters, where life could once have come from the outside (even in a very primitive form), and could survive to this day. Moreover, according to some model's assumptions, Io could sometime be formed in another part of the Solar system, where the water could exist. Note that on neighboring Galilean satellites now exist significant amounts of water .

  7. A Commercial Architecture for Satellite Imagery

    National Research Council Canada - National Science Library

    Didier, Christopher J

    2006-01-01

    .... This study focuses on the concept of the U.S. government purchasing proven and successful commercial satellites with minimal non-recurring engineering costs to help augment current national systems...

  8. Formation Flying/Satellite Swarm Concept Project

    Science.gov (United States)

    Youngquist, Robert C.

    2014-01-01

    NASA needs a method of not only propelling and rotating small satellites, but also to track their position and orientation. We propose a concept that will, for the first time, demonstrate both tracking and propulsion simultaneously in the same system.

  9. Software for validating parameters retrieved from satellite

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; Sathe, P.V.; Pankajakshan, T.

    -channel Scanning Microwave Radiometer (MSMR) onboard the Indian satellites Occansat-1 during 1999-2001 were validated using this software as a case study. The program has several added advantages over the conventional method of validation that involves strenuous...

  10. New GOES satellite synchronized time code generation

    Science.gov (United States)

    Fossler, D. E.; Olson, R. K.

    1984-01-01

    The TRAK Systems' GOES Satellite Synchronized Time Code Generator is described. TRAK Systems has developed this timing instrument to supply improved accuracy over most existing GOES receiver clocks. A classical time code generator is integrated with a GOES receiver.

  11. Reusable Communication Infrastructure for Small Satellites

    Data.gov (United States)

    National Aeronautics and Space Administration — The research goal of this project is to develop a comprehensive communications reference architecture that is applicable to a wide variety of small satellite...

  12. A new digital land mobile satellite system

    Science.gov (United States)

    Schneider, Philip

    A description is given of the different digital services planned to be carried over existing and planned mobile satellite systems. These systems are then compared with analog services in terms of bandwidth and power efficiency. This comparison provides the rationale for the establishment of a digital land mobile satellite service (DLMSS) to use frequencies that are currently available but not yet assigned to a domestic mobile satellite system in the United States. The focus here is on the expected advantages of digital transmission techniques in accommodating additional mobile satellite systems in this portion of the spectrum, and how such techniques can fully satisfy voice, data and facsimile mobile communications requirements in a cost effective manner. A description is given of the system architecture of the DMLSS service proposed by the Geostar Messaging Corporation (GMC) and the market potential of DLMSS.

  13. Orbit determination for ISRO satellite missions

    Science.gov (United States)

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

    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

  14. A Survey of Satellite Communications System Vulnerabilities

    National Research Council Canada - National Science Library

    Steinberger, Jessica A

    2008-01-01

    The U.S. military's increasing reliance on commercial and military communications satellites to enable widely-dispersed, mobile forces to communicate makes these space assets increasingly vulnerable to attack by adversaries...

  15. Smartphone Video Guidance Sensor for Small Satellites

    Data.gov (United States)

    National Aeronautics and Space Administration — Smartphone Video Guidance Sensor(SVGS) for Small Satellites will provide a low-cost,integrated rendezvous & proximity operations sensor system to allow an...

  16. Micro Resistojet for Small Satellites, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Micro-resistojets offer an excellent combination of simplicity, performance and wet system mass for small satellites (<100 kg, <50 watts) requiring mN level...

  17. Defense Meteorological Satellite Program (DMSP) Film

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The United States Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) is a polar orbiting meteorological sensor with two...

  18. Virtual Satellite Integration Environment, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Advatech Pacific proposes to develop a Virtual Satellite Integration Environment (VSIE) for the NASA Ames Mission Design Center. The VSIE introduces into NASA...

  19. Selected Geomagnetic Measurements From Several Satellites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — More than 17 million selected magnetic observations from several orbiting low-altitude satellites are contained in this digital collection. Except for MAGSAT, all...

  20. ECAPS - Eddy Current Approach and Proximity Satellites

    Data.gov (United States)

    National Aeronautics and Space Administration — Multiple, energized coils in a small satellite will generate eddy currents in the skin of the International Space Station (ISS). This will create repulsive forces...

  1. High power communication satellites power systems study

    Science.gov (United States)

    Josloff, Allan T.; Peterson, Jerry R.

    1995-01-01

    This paper discusses a planned study to evaluate the commercial attractiveness of high power communication satellites and assesses the attributes of both conventional photovoltaic and reactor power systems. These high power satellites can play a vital role in assuring availability of universally accessible, wide bandwidth communications, for high definition TV, super computer networks and other services. Satellites are ideally suited to provide the wide bandwidths and data rates required and are unique in the ability to provide services directly to the users. As new or relocated markets arise, satellites offer a flexibility that conventional distribution services cannot match, and it is no longer necessary to be near population centers to take advantage of the telecommunication revolution. The geopolitical implications of these substantially enhanced communications capabilities can be significant.

  2. Micro Resistojet for Small Satellites, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Micro-resistojets offer the best combination of simplicity, performance, wet system mass and power consumption for small satellites (<100kg, <50Watts)...

  3. Virtual Satellite Integration Environment, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — An integrated environment for rapid design studies of small satellite missions will be developed. This environment will be designed to streamline processes at the...

  4. Thermal Conductivity Measurements on Icy Satellite Analogs

    Science.gov (United States)

    Javeed, Aurya; Barmatz, Martin; Zhong, Fang; Choukroun, Mathieu

    2012-01-01

    With regard to planetary science, NASA aspires to: "Advance scientific knowledge of the origin and history of the solar system, the potential for life elsewhere, and the hazards and resources present as humans explore space". In pursuit of such an end, the Galileo and Cassini missions garnered spectral data of icy satellite surfaces implicative of the satellites' structure and material composition. The potential for geophysical modeling afforded by this information, coupled with the plausibility of life on icy satellites, has pushed Jupiter's Europa along with Saturn's Enceladus and Titan toward the fore of NASA's planetary focus. Understanding the evolution of, and the present processes at work on, the aforementioned satellites falls squarely in-line with NASA's cited goal.

  5. Land mobile satellite services in Europe

    Science.gov (United States)

    Bartholomé, P.; Berretta, G.; Rogard, R.

    The demand for land-mobile communications on a Europe-wide basis is an important and pressing problem. The pan-European cellular network now in the planning stage will be slow in coming and it will have its limitations. A regional satellite system for Europe to complement the cellular network is the only practical way to satisfy a specialised market that encompasses a population of several hundred thousand mobiles, including road vehicles, merchant shipping, fishing boats, and trains. The deployment of a regional system would take place in a number of phases, the first being based on a simple payload embarked on a host satellite belonging to a European organisation. Further phases will involve the development of more advanced payloads on dedicated satellites. For the long-term future, the use of satellites in highly inclined orbits is being considered as a means of improving their visibility and hence the service quality.

  6. Satellite Formation Control Using Atmospheric Drag

    National Research Council Canada - National Science Library

    Hajovsky, Blake B

    2007-01-01

    This study investigates the use of a linear quadratic terminal controller to reconfigure satellite formations using atmospheric drag actuated control while minimizing the loss of energy of the formation...

  7. Space industrialization - Education. [via communication satellites

    Science.gov (United States)

    Joels, K. M.

    1978-01-01

    The components of an educational system based on, and perhaps enhanced by, space industrialization communications technology are considered. Satellite technology has introduced a synoptic distribution system for various transmittable educational media. The cost of communications satellite distribution for educational programming has been high. It has, therefore, been proposed to utilize Space Shuttle related technology and Large Space Structures (LSS) to construct a system with a quantum advancement in communication capability and a quantum reduction in user cost. LSS for communications purposes have three basic advantages for both developed and emerging nations, including the ability to distribute signals over wide geographic areas, the reduced cost of satellite communications systems versus installation of land based systems, and the ability of a communication satellite system to create instant educational networks.

  8. Experimental Satellite Phase 3D before Launch

    Directory of Open Access Journals (Sweden)

    J. Sebesta

    1999-04-01

    Full Text Available To build a satellite can be a dream for many engineers. We are happy that we can participate in the AMSAT PHASE 3D project. Our responsibility is very high because one of our on-board receivers is the main one of the command link and will never be switched off. The project is also a very good opportunity for our students to meet satellite technology.

  9. Small Satellite Constellations for Geospace Sciences

    Science.gov (United States)

    Spence, H. E.

    2016-12-01

    The recent National Academy of Sciences Solar and Space Physics Decadal Survey (DS) identified community-consensus science priorities for the decade spanning 2013 - 2022. In this talk, we discuss the ways by which small satellite constellations are already and may soon accelerate progress toward achieving many of these science targets. The DS outlined four overarching science goals: (1) determine the origins of the Sun's activity and predict the variations in the space environment; (2) determine the dynamics and coupling of Earth's magnetosphere, ionosphere, and atmosphere and their response to solar and terrestrial inputs; (3) determine the interaction of the Sun with the solar system and the interstellar medium; and, (4) discover and characterize fundamental processes that occur both within the heliosphere and throughout the universe. These DS science goals provide the context for key science challenges in the three connected parts of the system that encompass all of solar and space physics, herein referred to as geospace: the Sun and heliosphere; the coupled solar wind-magnetosphere system; and, the coupled atmosphere-ionosphere-magnetosphere system. The DS further presented the role that small satellites play in resolving many of these science challenges, with a particular emphasis on the role that constellations of small satellites will play. While once considered by many as being "futuristic" or even "unrealizable", constellations of small satellites are already making important contributions to geospace science and with the promise for more to come. Using the DS as a guidepost, in this presentation, we outline representative small satellite constellation missions alread underway, some in development, and others notionally proposed over the next several years that employ small satellite constellations to tackle large science imperatives. Finally, we give examples of key small satellite technologies in development that will potentially enable great scientific

  10. DUBNA-GRAN SASSO: Satellite computer link

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    In April a 64 kbit/s computer communication link was set up between the Joint Institute for Nuclear Research (JINR), Dubna (Russia) and Gran Sasso (Italy) Laboratories via nearby ground satellite stations using the INTELSAT V satellite. Previously the international community of Dubna's experimentalists and theorists (high energy physics, condensed matter physics, low energy nuclear and neutron physics, accelerator and applied nuclear physics) had no effective computer links with scientific centres worldwide

  11. Satellite Remote Sensing in Seismology. A Review

    Directory of Open Access Journals (Sweden)

    Andrew A. Tronin

    2009-12-01

    Full Text Available A wide range of satellite methods is applied now in seismology. The first applications of satellite data for earthquake exploration were initiated in the ‘70s, when active faults were mapped on satellite images. It was a pure and simple extrapolation of airphoto geological interpretation methods into space. The modern embodiment of this method is alignment analysis. Time series of alignments on the Earth's surface are investigated before and after the earthquake. A further application of satellite data in seismology is related with geophysical methods. Electromagnetic methods have about the same long history of application for seismology. Stable statistical estimations of ionosphere-lithosphere relation were obtained based on satellite ionozonds. The most successful current project "DEMETER" shows impressive results. Satellite thermal infra-red data were applied for earthquake research in the next step. Numerous results have confirmed previous observations of thermal anomalies on the Earth's surface prior to earthquakes. A modern trend is the application of the outgoing long-wave radiation for earthquake research. In ‘80s a new technology—satellite radar interferometry—opened a new page. Spectacular pictures of co-seismic deformations were presented. Current researches are moving in the direction of pre-earthquake deformation detection. GPS technology is also widely used in seismology both for ionosphere sounding and for ground movement detection. Satellite gravimetry has demonstrated its first very impressive results on the example of the catastrophic Indonesian earthquake in 2004. Relatively new applications of remote sensing for seismology as atmospheric sounding, gas observations, and cloud analysis are considered as possible candidates for applications.

  12. Time-Zone-Pattern Satellite Broadcasting Antenna

    Science.gov (United States)

    Galindo, Victor; Rahmat-Samii, Yahya; Imbriale, William A.; Cohen, Herb; Cagnon, Ronald R.

    1988-01-01

    Direct-broadcast satellite antenna designs provide contoured beams to match four time zones in 48 contiguous states and spot beams for Alaska, Hawaii, and Puerto Rico presented in 29-page report. Includes descriptions of procedures used to arrive at optimized designs. Arrangements, amplitudes, and phases of antenna feeds presented in tables. Gain contours shown graphically. Additional tables of performance data given for cities in service area of Eastern satellite.

  13. Astrometry and Geostationary Satellites in Venezuela

    Science.gov (United States)

    Lacruz, E.; Abad, C.

    2015-10-01

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

  14. MEMS for pico- to micro-satellites

    OpenAIRE

    Shea, Herbert

    2009-01-01

    MEMS sensors, actuators, and sub-systems can enable an important reduction in the size and mass of spacecrafts, first by replacing larger and heavier components, then by replacing entire subsystems, and finally by enabling the microfabrication of highly integrated picosats. Very small satellites (1 to 100 kg) stand to benefit the most from MEMS technologies. These small satellites are typically used for science or technology demonstration missions, with higher risk tolerance than multi-ton te...

  15. Leo satellite-based telecommunication network concepts

    Science.gov (United States)

    Aiken, John G.; Swan, Peter A.; Leopold, Ray J.

    1991-01-01

    Design considerations are discussed for Low Earth Orbit (LEO) satellite based telecommunications networks. The satellites are assumed to be connected to each other via intersatellite links. They are connected to the end user either directly or through gateways to other networks. Frequency reuse, circuit switching, packet switching, call handoff, and routing for these systems are discussed by analogy with terrestrial cellular (mobile radio) telecommunication systems.

  16. Dynamics of satellites, asteroids, and rings

    International Nuclear Information System (INIS)

    Dermott, S.F.

    1987-01-01

    Work is reported on: (1) the shapes and the internal structures of satellites; (2) the tidal heating of Miranda; (3) the dynamics of arc-like rings; and (4) the structure of the zodiacal cloud that was revealed by the Infrared Astronomy Satellite. Significant progress was made in determining the shape and internal structure of Mimas and in understanding the dynamical evolution of Miranda's orbit

  17. Volumetric Forest Change Detection Through Vhr Satellite Imagery

    Science.gov (United States)

    Akca, Devrim; Stylianidis, Efstratios; Smagas, Konstantinos; Hofer, Martin; Poli, Daniela; Gruen, Armin; Sanchez Martin, Victor; Altan, Orhan; Walli, Andreas; Jimeno, Elisa; Garcia, Alejandro

    2016-06-01

    Quick and economical ways of detecting of planimetric and volumetric changes of forest areas are in high demand. A research platform, called FORSAT (A satellite processing platform for high resolution forest assessment), was developed for the extraction of 3D geometric information from VHR (very-high resolution) imagery from satellite optical sensors and automatic change detection. This 3D forest information solution was developed during a Eurostars project. FORSAT includes two main units. The first one is dedicated to the geometric and radiometric processing of satellite optical imagery and 2D/3D information extraction. This includes: image radiometric pre-processing, image and ground point measurement, improvement of geometric sensor orientation, quasiepipolar image generation for stereo measurements, digital surface model (DSM) extraction by using a precise and robust image matching approach specially designed for VHR satellite imagery, generation of orthoimages, and 3D measurements in single images using mono-plotting and in stereo images as well as triplets. FORSAT supports most of the VHR optically imagery commonly used for civil applications: IKONOS, OrbView - 3, SPOT - 5 HRS, SPOT - 5 HRG, QuickBird, GeoEye-1, WorldView-1/2, Pléiades 1A/1B, SPOT 6/7, and sensors of similar type to be expected in the future. The second unit of FORSAT is dedicated to 3D surface comparison for change detection. It allows users to import digital elevation models (DEMs), align them using an advanced 3D surface matching approach and calculate the 3D differences and volume changes between epochs. To this end our 3D surface matching method LS3D is being used. FORSAT is a single source and flexible forest information solution with a very competitive price/quality ratio, allowing expert and non-expert remote sensing users to monitor forests in three and four dimensions from VHR optical imagery for many forest information needs. The capacity and benefits of FORSAT have been tested in

  18. Major Limitations of Satellite images

    OpenAIRE

    Al-Wassai, Firouz A.; Kalyankar, N. V.

    2013-01-01

    Remote sensing has proven to be a powerful tool for the monitoring of the Earth surface to improve our perception of our surroundings has led to unprecedented developments in sensor and information technologies. However, technologies for effective use of the data and for extracting useful information from the data of Remote sensing are still very limited since no single sensor combines the optimal spectral, spatial and temporal resolution. This paper briefly reviews the limitations of satelli...

  19. The reionization of galactic satellite populations

    Energy Technology Data Exchange (ETDEWEB)

    Ocvirk, P.; Gillet, N.; Aubert, D.; Chardin, J. [Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS UMR 7550, 11 rue de l' Université, F-67000 Strasbourg (France); Knebe, A.; Yepes, G. [Grupo de Astrofísica, Departamento de Fisica Teorica, Modulo C-8, Universidad Autónoma de Madrid, Cantoblanco E-280049 (Spain); Libeskind, N.; Gottlöber, S. [Leibniz-Institute für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Hoffman, Y. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

    2014-10-10

    We use high-resolution simulations of the formation of the local group, post-processed by a radiative transfer code for UV photons, to investigate the reionization of the satellite populations of an isolated Milky Way-M31 galaxy pair in a variety of scenarios. We use an improved version of ATON which includes a simple recipe for radiative feedback. In our baseline models, reionization is initiated by low-mass, radiatively regulated halos at high redshift, until more massive halos appear, which then dominate and complete the reionization process. We investigate the relation between reionization history and present-day positions of the satellite population. We find that the average reionization redshift (z {sub r}) of satellites is higher near galaxy centers (MW and M31). This is due to the inside out reionization patterns imprinted by massive halos within the progenitor during the epoch of reionization, which end up forming the center of the galaxy. Due to incomplete dynamical mixing during galaxy assembly, these early patterns survive to present day, resulting in a clear radial gradient in the average satellite reionization redshift, up to the virial radius of MW and M31 and beyond. In the lowest emissivity scenario, the outer satellites are reionized about 180 Myr later than the inner satellites. This delay decreases with increasing source model emissivity, or in the case of external reionization by Virgo or M31, because reionization occurs faster overall and becomes spatially quasi-uniform at the highest emissivity.

  20. The reionization of galactic satellite populations

    International Nuclear Information System (INIS)

    Ocvirk, P.; Gillet, N.; Aubert, D.; Chardin, J.; Knebe, A.; Yepes, G.; Libeskind, N.; Gottlöber, S.; Hoffman, Y.

    2014-01-01

    We use high-resolution simulations of the formation of the local group, post-processed by a radiative transfer code for UV photons, to investigate the reionization of the satellite populations of an isolated Milky Way-M31 galaxy pair in a variety of scenarios. We use an improved version of ATON which includes a simple recipe for radiative feedback. In our baseline models, reionization is initiated by low-mass, radiatively regulated halos at high redshift, until more massive halos appear, which then dominate and complete the reionization process. We investigate the relation between reionization history and present-day positions of the satellite population. We find that the average reionization redshift (z r ) of satellites is higher near galaxy centers (MW and M31). This is due to the inside out reionization patterns imprinted by massive halos within the progenitor during the epoch of reionization, which end up forming the center of the galaxy. Due to incomplete dynamical mixing during galaxy assembly, these early patterns survive to present day, resulting in a clear radial gradient in the average satellite reionization redshift, up to the virial radius of MW and M31 and beyond. In the lowest emissivity scenario, the outer satellites are reionized about 180 Myr later than the inner satellites. This delay decreases with increasing source model emissivity, or in the case of external reionization by Virgo or M31, because reionization occurs faster overall and becomes spatially quasi-uniform at the highest emissivity.

  1. Capture of irregular satellites at Jupiter

    International Nuclear Information System (INIS)

    Nesvorný, David; Vokrouhlický, David; Deienno, Rogerio

    2014-01-01

    The irregular satellites of outer planets are thought to have been captured from heliocentric orbits. The exact nature of the capture process, however, remains uncertain. We examine the possibility that irregular satellites were captured from the planetesimal disk during the early solar system instability when encounters between the outer planets occurred. Nesvorný et al. already showed that the irregular satellites of Saturn, Uranus, and Neptune were plausibly captured during planetary encounters. Here we find that the current instability models present favorable conditions for capture of irregular satellites at Jupiter as well, mainly because Jupiter undergoes a phase of close encounters with an ice giant. We show that the orbital distribution of bodies captured during planetary encounters provides a good match to the observed distribution of irregular satellites at Jupiter. The capture efficiency for each particle in the original transplanetary disk is found to be (1.3-3.6) × 10 –8 . This is roughly enough to explain the observed population of jovian irregular moons. We also confirm Nesvorný et al.'s results for the irregular satellites of Saturn, Uranus, and Neptune.

  2. SDI satellite autonomy using AI and Ada

    Science.gov (United States)

    Fiala, Harvey E.

    1990-01-01

    The use of Artificial Intelligence (AI) and the programming language Ada to help a satellite recover from selected failures that could lead to mission failure are described. An unmanned satellite will have a separate AI subsystem running in parallel with the normal satellite subsystems. A satellite monitoring subsystem (SMS), under the control of a blackboard system, will continuously monitor selected satellite subsystems to become alert to any actual or potential problems. In the case of loss of communications with the earth or the home base, the satellite will go into a survival mode to reestablish communications with the earth. The use of an AI subsystem in this manner would have avoided the tragic loss of the two recent Soviet probes that were sent to investigate the planet Mars and its moons. The blackboard system works in conjunction with an SMS and a reconfiguration control subsystem (RCS). It can be shown to be an effective way for one central control subsystem to monitor and coordinate the activities and loads of many interacting subsystems that may or may not contain redundant and/or fault-tolerant elements. The blackboard system will be coded in Ada using tools such as the ABLE development system and the Ada Production system.

  3. An optimization tool for satellite equipment layout

    Science.gov (United States)

    Qin, Zheng; Liang, Yan-gang; Zhou, Jian-ping

    2018-01-01

    Selection of the satellite equipment layout with performance constraints is a complex task which can be viewed as a constrained multi-objective optimization and a multiple criteria decision making problem. The layout design of a satellite cabin involves the process of locating the required equipment in a limited space, thereby satisfying various behavioral constraints of the interior and exterior environments. The layout optimization of satellite cabin in this paper includes the C.G. offset, the moments of inertia and the space debris impact risk of the system, of which the impact risk index is developed to quantify the risk to a satellite cabin of coming into contact with space debris. In this paper an optimization tool for the integration of CAD software as well as the optimization algorithms is presented, which is developed to automatically find solutions for a three-dimensional layout of equipment in satellite. The effectiveness of the tool is also demonstrated by applying to the layout optimization of a satellite platform.

  4. Artificial Satellites and How to Observe Them

    CERN Document Server

    Schmude, Jr , Richard

    2012-01-01

    Astronomers' Observing Guides provide up-to-date information for amateur astronomers who want to know all about what it is they are observing. This is the basis for the first part of the book. The second part details observing techniques for practical astronomers, working with a range of different instruments. Every amateur astronomer sees "stars" that aren't natural objects steadily slide across the background of the sky. Artificial satellites can be seen on any night, and some are as bright as the planets. But can you identify which satellite or spent launch vehicle casing you are seeing? Do you know how to image it? Artificial Satellites and How to Observe Them describes all of the different satellites that can be observed, including communication, scientific, spy satellites, and of course, the International Space Station. Richard Schmude describes how to recognize them and even how to predict their orbits. The book tells how to observe artificial satellites with the unaided eye, binoculars and with telesc...

  5. Satellite outreach in Asia and the Pacific.

    Science.gov (United States)

    1977-01-01

    Communication by satellite is rapidly changing information exchange in Asia, especially for rural areas. The integrated education planned for satellite networks includes family planning as part of general development. A series of conferences has already been held successfully via satellite for family planning associations who are members of the East and Southeast Asia and Oceania Region of the International Planned Parenthood Federation. These included a conference on nursing training. In India the Satellite Instructional Television Experiment (SITE) made history during its 1-year trial. By 1981 the entire nation is to be linked by satellite. The question is whether the television education will truly change rural life or whether it will become merely a diversion. In Indonesia, satellites were chosen as the fastest way to obtain interisland communication. The Domsat system links the entire 13,000-island archipelago and is already being used for emergency communications. The system, which was developed in 1 1/2 years by the Hughes Aircraft Corporation will be used for teaching basic health, hygiene, and family planning. It will be several years before Domsat is fully operational, but it bears watching.

  6. 47 CFR 25.279 - Inter-satellite service.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Inter-satellite service. 25.279 Section 25.279 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations § 25.279 Inter-satellite service. (a) Any satellite communicating with other space...

  7. Education and the Satellite: Possibilities for Saudi Arabia?

    Science.gov (United States)

    Al-Sharhan, Jamal

    2000-01-01

    Discussion of developments in satellite communications and educational applications focuses on the possibilities of adapting satellite technology for instruction in developing countries. Topics include satellite use in Australia and the United States; and recommendations for the adoption of satellite technology in Saudi Arabia. (Author/LRW)

  8. The Emerging Trends in Satellite and Wireless Communications ...

    Indian Academy of Sciences (India)

    Table of contents. The Emerging Trends in Satellite and Wireless Communications Technologies · Satellite Communications · Communications Satellites for Global Coverage · Satellite Transponders · The Four Generations Of Commercial Communication Geo-Sat · PowerPoint Presentation · An Indian Scenario INSAT ...

  9. Using satellite communications for a mobile computer network

    Science.gov (United States)

    Wyman, Douglas J.

    1993-01-01

    The topics discussed include the following: patrol car automation, mobile computer network, network requirements, network design overview, MCN mobile network software, MCN hub operation, mobile satellite software, hub satellite software, the benefits of patrol car automation, the benefits of satellite mobile computing, and national law enforcement satellite.

  10. Bottom Pressure Tides Along a Line in the Southeast Atlantic Ocean and Comparisons with Satellite Altimetry

    Science.gov (United States)

    Ray, Richard D.; Byrne, Deidre A.

    2010-01-01

    Seafloor pressure records, collected at 11 stations aligned along a single ground track of the Topex/Poseidon and Jason satellites, are analyzed for their tidal content. With very low background noise levels and approximately 27 months of high-quality records, tidal constituents can be estimated with unusually high precision. This includes many high-frequency lines up through the seventh-diurnal band. The station deployment provides a unique opportunity to compare with tides estimated from satellite altimetry, point by point along the satellite track, in a region of moderately high mesoscale variability. That variability can significantly corrupt altimeter-based tide estimates, even with 17 years of data. A method to improve the along-track altimeter estimates by correcting the data for nontidal variability is found to yield much better agreement with the bottom-pressure data. The technique should prove useful in certain demanding applications, such as altimetric studies of internal tides.

  11. Rapid core field variations during the satellite era: Investigations using stochastic process based field models

    DEFF Research Database (Denmark)

    Finlay, Chris; Olsen, Nils; Gillet, Nicolas

    We present a new ensemble of time-dependent magnetic field models constructed from satellite and observatory data spanning 1997-2013 that are compatible with prior information concerning the temporal spectrum of core field variations. These models allow sharper field changes compared to tradition...... physical hypotheses can be tested by asking questions of the entire ensemble of core field models, rather than by interpreting any single model.......We present a new ensemble of time-dependent magnetic field models constructed from satellite and observatory data spanning 1997-2013 that are compatible with prior information concerning the temporal spectrum of core field variations. These models allow sharper field changes compared to traditional...... regularization methods based on minimizing the square of second or third time derivative. We invert satellite and observatory data directly by adopting the external field and crustal field modelling framework of the CHAOS model, but apply the stochastic process method of Gillet et al. (2013) to the core field...

  12. A Large Scale Problem Based Learning inter-European Student Satellite Construction Project

    DEFF Research Database (Denmark)

    Nielsen, Jens Frederik Dalsgaard; Alminde, Lars; Bisgaard, Morten

    2006-01-01

    that electronic communication technology was vital within the project. Additionally the SSETI EXPRESS project implied the following problems it didn’t fit to a standard semester - 18 months for the satellite project compared to 5/6 months for a “normal” semester project. difficulties in integrating the tasks......A LARGE SCALE PROBLEM BASED LEARNING INTER-EUROPEAN STUDENT SATELLITE CONSTRUCTION PROJECT This paper describes the pedagogical outcome of a large scale PBL experiment. ESA (European Space Agency) Education Office launched January 2004 an ambitious project: Let students from all over Europe build....... The satellite was successfully launched on October 27th 2005 (http://www.express.space.aau.dk). The project was a student driven project with student project responsibility adding at lot of international experiences and project management skills to the outcome of more traditional one semester, single group...

  13. Single bunched beam generation without subharmonic prebuncher

    International Nuclear Information System (INIS)

    Kobayashi, T.; Tagawa, S.

    1995-01-01

    The intensity of the accelerated single bunched electron beam depends on the performance of the electron gun and the fast cathode pulser. The electron beam is emitted by a Y-796 cathode assembly with a cathode of 2 cm 2 (8 A/cm 2 ), and an extracted voltage of 90 kV. The maximum charge of the single bunched beam was attained at 1.5 nC/pulse using SHB. Recently, a single bunched beam has been generated by an ultrafast cathode pulser (rise and fall time <100 ps pulse height -2 kV at 50 Ω) without SHB. The charge of the accelerated electron beam is about 40 pC/pulse (pulse width <10 ps) without the production of a satellite beam. This result show that a single bunched beam can be produced by the linear accelerator without SHB. ((orig.))

  14. Japanese Global Precipitation Measurement (GPM) mission status and application of satellite-based global rainfall map

    Science.gov (United States)

    Kachi, Misako; Shimizu, Shuji; Kubota, Takuji; Yoshida, Naofumi; Oki, Riko; Kojima, Masahiro; Iguchi, Toshio; Nakamura, Kenji

    2010-05-01

    As accuracy of satellite precipitation estimates improves and observation frequency increases, application of those data to societal benefit areas, such as weather forecasts and flood predictions, is expected, in addition to research of precipitation climatology to analyze precipitation systems. There is, however, limitation on single satellite observation in coverage and frequency. Currently, the Global Precipitation Measurement (GPM) mission is scheduled under international collaboration to fulfill various user requirements that cannot be achieved by the single satellite, like the Tropical Rainfall Measurement Mission (TRMM). The GPM mission is an international mission to achieve high-accurate and high-frequent rainfall observation over a global area. GPM is composed of a TRMM-like non-sun-synchronous orbit satellite (GPM core satellite) and constellation of satellites carrying microwave radiometer instruments. The GPM core satellite carries the Dual-frequency Precipitation Radar (DPR), which is being developed by the Japan Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT), and microwave radiometer provided by the National Aeronautics and Space Administration (NASA). Development of DPR instrument is in good progress for scheduled launch in 2013, and DPR Critical Design Review has completed in July - September 2009. Constellation satellites, which carry a microwave imager and/or sounder, are planned to be launched around 2013 by each partner agency for its own purpose, and will contribute to extending coverage and increasing frequency. JAXA's future mission, the Global Change Observation Mission (GCOM) - Water (GCOM-W) satellite will be one of constellation satellites. The first generation of GCOM-W satellite is scheduled to be launched in 2011, and it carries the Advanced Microwave Scanning Radiometer 2 (AMSR2), which is being developed based on the experience of the AMSR-E on EOS Aqua satellite

  15. A Space Based Solar Power Satellite System

    Science.gov (United States)

    Engel, J. M.; Polling, D.; Ustamujic, F.; Yaldiz, R.; et al.

    2002-01-01

    (SPoTS) supplying other satellites with energy. SPoTS is due to be commercially viable and operative in 2020. of Technology designed the SPoTS during a full-time design period of six weeks as a third year final project. The team, organized according to the principles of systems engineering, first conducted a literature study on space wireless energy transfer to select the most suitable candidates for use on the SPoTS. After that, several different system concepts have been generated and evaluated, the most promising concept being worked out in greater detail. km altitude. Each SPoTS satellite has a 50m diameter inflatable solar collector that focuses all received sunlight. Then, the received sunlight is further redirected by means of four pointing mirrors toward four individual customer satellites. A market-analysis study showed, that providing power to geo-stationary communication satellites during their eclipse would be most beneficial. At arrival at geo-stationary orbit, the focused beam has expended to such an extent that its density equals one solar flux. This means that customer satellites can continue to use their regular solar arrays during their eclipse for power generation, resulting in a satellite battery mass reduction. the customer satellites in geo-stationary orbit, the transmitted energy beams needs to be pointed with very high accuracy. Computations showed that for this degree of accuracy, sensors are needed, which are not mainstream nowadays. Therefore further research must be conducted in this area in order to make these high-accuracy-pointing systems commercially attractive for use on the SPoTS satellites around 2020. Total 20-year system lifetime cost for 18 SPoT satellites are estimated at approximately USD 6 billion [FY2001]. In order to compete with traditional battery-based satellite power systems or possible ground based wireless power transfer systems the price per kWh for the customer must be significantly lower than the present one

  16. GNSS-SLR satellite co-location for the estimate of local ties

    Science.gov (United States)

    Bruni, Sara; Zerbini, Susanna; Errico, Maddalena; Santi, Efisio

    2013-04-01

    The current realization of the International Terrestrial Reference Frame (ITRF) is based on four different space-geodetic techniques, so that the benefits brought by each observing system to the definition of the frame can compensate for the drawbacks of the others and technique-specific systematic errors might be identified. The strategy used to combine the observations from the different techniques is then of prominent importance for the realization of a precise and stable reference frame. This study concentrates, in particular, on the combination of Satellite Laser Ranging (SLR) and Global Navigation Satellite System (GNSS) observations by exploiting satellite co-locations. This innovative approach is based on the fact that laser tracking of GNSS satellites, carrying on board laser reflector arrays, allows for the combination of optical and microwave signals in the determination of the spacecraft orbit. Besides, the use of satellite co-locations differs quite significantly from the traditional combination method in which each single technique solution is carried out autonomously and is interrelated in a second step. One of the benefits of the approach adopted in this study is that it allows for an independent validation of the local tie, i.e. of the vector connecting the SLR and GNSS reference points in a multi-techniques station. Typically, local ties are expressed by a single value, measured with ground-based geodetic techniques and taken as constant. In principle, however, local ties might show time variations likely caused by the different monumentation characteristics of the GNSS antennas with respect to those of a SLR system. This study evaluates the possibility of using the satellite co-location approach to generate local-ties time series by means of observations available for a selected network of ILRS stations. The data analyzed in this study were acquired as part of the NASA's Earth Science Data Systems and are archived and distributed by the Crustal

  17. ASAP- ARTIFICIAL SATELLITE ANALYSIS PROGRAM

    Science.gov (United States)

    Kwok, J.

    1994-01-01

    The Artificial Satellite Analysis Program (ASAP) is a general orbit prediction program which incorporates sufficient orbit modeling accuracy for mission design, maneuver analysis, and mission planning. ASAP is suitable for studying planetary orbit missions with spacecraft trajectories of reconnaissance (flyby) and exploratory (mapping) nature. Sample data is included for a geosynchronous station drift cycle study, a Venus radar mapping strategy, a frozen orbit about Mars, and a repeat ground trace orbit. ASAP uses Cowell's method in the numerical integration of the equations of motion. The orbital mechanics calculation contains perturbations due to non-sphericity (up to a 40 X 40 field) of the planet, lunar and solar effects, and drag and solar radiation pressure. An 8th order Runge-Kutta integration scheme with variable step size control is used for efficient propagation. The input includes the classical osculating elements, orbital elements of the sun relative to the planet, reference time and dates, drag coefficient, gravitational constants, and planet radius, rotation rate, etc. The printed output contains Cartesian coordinates, velocity, equinoctial elements, and classical elements for each time step or event step. At each step, selected output is added to a plot file. The ASAP package includes a program for sorting this plot file. LOTUS 1-2-3 is used in the supplied examples to graph the results, but any graphics software package could be used to process the plot file. ASAP is not written to be mission-specific. Instead, it is intended to be used for most planetary orbiting missions. As a consequence, the user has to have some basic understanding of orbital mechanics to provide the correct input and interpret the subsequent output. ASAP is written in FORTRAN 77 for batch execution and has been implemented on an IBM PC compatible computer operating under MS-DOS. The ASAP package requires a math coprocessor and a minimum of 256K RAM. This program was last

  18. The escape of natural satellites from Mercury and Venus

    International Nuclear Information System (INIS)

    Kumar, S.S.

    1977-01-01

    It is suggested that the slow rotations of Mercury and Venus may be connected with the absence of natural satellites around them. If Mercury or Venus possessed a satellite at the time of formation, the tidal evolution would have caused the satellite to recede. At a sufficiently large distance from the planet, the Sun's gravitational influence makes the satellite orbit unstable. The natural satellites of Mercury and Venus might have escaped as a consequence of this instability. (Auth.)

  19. Escape of natural satellites from Mercury and Venus

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S S [Virginia Univ., Charlottesville (USA)

    1977-09-01

    It is suggested that the slow rotations of Mercury and Venus may be connected with the absence of natural satellites around them. If Mercury or Venus possessed a satellite at the time of formation, the tidal evolution would have caused the satellite to recede. At a sufficiently large distance from the planet, the Sun's gravitational influence makes the satellite orbit unstable. The natural satellites of Mercury and Venus might have escaped as a consequence of this instability.

  20. Equalization and detection for digital communication over nonlinear bandlimited satellite communication channels. Ph.D. Thesis

    Science.gov (United States)

    Gutierrez, Alberto, Jr.

    1995-01-01

    This dissertation evaluates receiver-based methods for mitigating the effects due to nonlinear bandlimited signal distortion present in high data rate satellite channels. The effects of the nonlinear bandlimited distortion is illustrated for digitally modulated signals. A lucid development of the low-pass Volterra discrete time model for a nonlinear communication channel is presented. In addition, finite-state machine models are explicitly developed for a nonlinear bandlimited satellite channel. A nonlinear fixed equalizer based on Volterra series has previously been studied for compensation of noiseless signal distortion due to a nonlinear satellite channel. This dissertation studies adaptive Volterra equalizers on a downlink-limited nonlinear bandlimited satellite channel. We employ as figure of merits performance in the mean-square error and probability of error senses. In addition, a receiver consisting of a fractionally-spaced equalizer (FSE) followed by a Volterra equalizer (FSE-Volterra) is found to give improvement beyond that gained by the Volterra equalizer. Significant probability of error performance improvement is found for multilevel modulation schemes. Also, it is found that probability of error improvement is more significant for modulation schemes, constant amplitude and multilevel, which require higher signal to noise ratios (i.e., higher modulation orders) for reliable operation. The maximum likelihood sequence detection (MLSD) receiver for a nonlinear satellite channel, a bank of matched filters followed by a Viterbi detector, serves as a probability of error lower bound for the Volterra and FSE-Volterra equalizers. However, this receiver has not been evaluated for a specific satellite channel. In this work, an MLSD receiver is evaluated for a specific downlink-limited satellite channel. Because of the bank of matched filters, the MLSD receiver may be high in complexity. Consequently, the probability of error performance of a more practical