WorldView

Class: Surveillance. Type: Civilian. Destination: Sun synchronous, 10:30 am descending node. Nation: USA. Agency: DigitalGlobe.

DigitalGlobe's WorldView satellite provided highly detailed imagery for precise map creation, change detection and in-depth image analysis. Best resolution available to commercian customers was 50 cm. However higher-resolution images were sold to DigitalGlobe's main customer, the US National Geospatial Intelligence Agency (NGA).

The sattelite was an ultra-stable 3-axis stabilized platform, using high-precision attitude sensors and GPS. Control Moment Gyros (CMGs) provided orientation and Star trackers, a solid state IRU, and GPS provided positional and orientation data . Rapid retargeting was possible using the Control Moment Gyros (>2x faster than any competitor) . WorldView collected, stored and downlinked a greater supply of frequently updated global imagery products than competitive systems. It offered the broadest range of collection sizes, without sacrificing capacity from small points to long strips and large areas.

Stereoscopic areas could be imaged on a single pass, ensuring image continuity and consistency of quality. Direct downlink to customer sites was available using the same high-speed 800 Mbps X-band downlink. This expedited image processing and delivery to customers where speed was a driving factor. WorldView extended the range of suitable imaging collection targets and enhanced image interpretability, because images could be acquired at even the lowest light levels. Frequent revisits increased image collection opportunities, enhanced change detection applications and enabled accurate map updates

Specifications

  • Highest resolution available commercially: 50 cm panchromatic at nadir / 55 cm out to 20° off-nadir
  • Geolocation Accuracy predicted performance in the range of 3.0 to 7.6 meters CE90, excluding terrain and off-nadir effects. With registration to GCPs in image: 2.0 meters (6.6 feet) CE90
  • 17.6 km width imaging swath (wider than any competitor)
  • 2199 gigabits on-board storage
  • 800 Mbps X-band data downlink
  • World-class telescope with high contrast (MTF) and signal to noise ratio, selectable Time Delay Integration (TDI) levels, 11-bit dynamic range
  • Revisits at high resolution: 1.7 days at 1 m GSD or less; 5.4 days at 20° off-nadir or less (51 cm GSD = Ground Sample Distance)
  • Orbit: 496 kilometers Sun synchronous, 10:30 am descending node, 94.6 minute period
  • Sensor Bands: Panchromatic
  • Panchromatic: Sensor Resolution: 0.50 meters GSD at nadir / 0.55 meters GSD at 20° off-nadir (note that imagery must be re-sampled to 0.5 meters for non-US Government customers)
  • Dynamic Range: 11-bits per pixel
  • Time Delay Integration (TDI): 6 selectable levels from 8 to 64
  • Swath Width: 17.6 kilometers at nadir
  • Pointing Accuracy & Knowledge: Accuracy: <500 meters at image start and stop Knowledge: Supports geolocation accuracy below
  • Retargeting Agility: Acceleration: 2.5 deg/s/s; Rate: 4.5 deg/s; Time to slew 300 kilometers: 9 seconds
  • Onboard Storage: 2199 gigabits solid state with EDAC
  • Communications: Image and Ancillary Data: 800 Mbps X-band; Housekeeping: 4, 16 or 32 kbps real-time, 524 kbps stored, X-band
  • Command: 2 or 64 kbps S-band
  • Max Viewing Angle / Accessible Ground Swath: Nominally +/-40° off-nadir = 858 km wide swath. Higher angles selectively available
  • Per Orbit Collection: 331 gigabits
  • Max Contiguous Area Collected in a Single Pass: 60 x 110 km mono; 30 x 110 km stereo
  • Revisit Frequency: 1.7 days at 1 meter GSD or less; 5.9 days at 20° off-nadir or less (0.51 meter GSD)
  • Geolocation Accuracy: Specification of 12.2m CE90, with predicted performance in the range of 3.0 to 7.6 meters (10 to 25 feet) CE90, excluding terrain and off-nadir effects; With registration to GCPs in image : 2.0 meters (6.6 feet)

Design Life: 7.25 years. Length: 2.50 m (8.20 ft). Basic Diameter: 3.60 m (11.80 ft). Maximum Diameter: 7.10 m (23.20 ft). Mass: 2,500 kg (5,500 lb). Electrical System: Solar array, 100 Ahr battery. Electric System: 3.20 kWh.


WorldView Chronology
  • 2007 September 18 - WorldView 1 - Launch Site: Vandenberg. Launch Vehicle: Delta 7000. Perigee: 492 km (305 mi). Apogee: 496 km (308 mi). Inclination: 97.50 deg. Period: 94.50 min.

    Spacecraft was equipped with a 0.6-m aperture telescope for high resolution surveillance. Civilian, but primary customer was to be the US National Geospatial Intelligence Agency.

 
 
 
 
 
 
 
 
 

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