Altitude and Slew Time

WorldView-1 provides earth imagery at 50cm spatial resolution. Being a panchromatic(Black & White) sensor, WorldView-1 can acquire very large areas in short period of time. This sensor was launched by DigitalGlobe on September 18, 2007. With an average revisit time of 1.7 days, WorldView-1 is capable of collecting up to 750,000 square kilometers (290,000 sq mi) per day of half-meter imagery.

Worldview-1 specifications

Launch InformationDate: September 18, 2007
Launch Vehicle: Delta II 7920
Launch Site: Vandenberg Air Force Base
OrbitAltitude: 496 kilometers
Type: Sun synchronous, 10:30 am descending node
Period: 94.6 minutes
Sensor BandsPanchromatic
Sensor Resolution (GSD = Ground Sample Distance)0.50 meters GSD at nadir
0.59 meters GSD at 25° off-nadir
NIIRS EquivalencyNIIRS potential of greater than 5.0
DynamicRange11-bits per pixel
Swath Width17.6 kilometers at nadir
Pointing Accuracy & KnowledgeAccuracy: <500 meters at image start and stop
Knowledge: Supports geolocation accuracy below
Retargeting AgilityAcceleration: 2.5 deg/s/s
Rate: 4.5 deg/s
Time to slew 300 kilometers: 10.5 seconds
Onboard Storage2199 gigabits solid state with EDAC
Max Viewing Angle / Accessible Ground SwathNominally +/-45° off-nadir = 1036 km wide swath Higher angles selectively available
Per Orbit Collection331 gigabits
Max Contiguous Area Collected in aSinglePass60 x 110 km mono 30 x 110 km stereo
Revisit Frequency1.7 days at 1 meter GSD 4.6 days at 25° off-nadir or less (0.59 meter GSD)
Geolocation Accuracy (CE90)Geolocation Accuracy specification of 6.5m CE90% at nadir, with actual accuracy in the range of 4.0 – 5.5m CE90%, excluding terrain and off-nadir effects

Ball Aerospace provided its BCP 5000 spacecraft bus, and the WorldView 60(Similar to the one used by QuickBird sensor) camera for the commercial imaging satellite.A new feature of the WorldView-1 spacecraft are CMG (Control Moment Gyroscopes) actuators for precise and highly responsive pointing control. The BCP-5000 bus provides increased power, stability, agility, data storage and transmission (over the BCP-2000 bus) as the demand for Earth remote-sensing information becomes more comprehensive.

The S/C is 3-axis stabilized. The ADCS (Attitude Determination and Control Subsystem) employs star trackers, IRU (Inertial Reference Unit) and GPS for attitude sensing, and CMGs as actuators. A S/C body-pointing range of ±40º about nadir is provided corresponding to a FOR (Field of Regard) of 775 km in cross-track. An instantaneous pointing accuracy of ≤ 500 m is provided at any start and stop of an imaging sequence. On the ground, the geolocation accuracy of the imagery is 5.8 to 7.6 m without GPCs (Ground Control Points) and 2 m with GPCs (3σ). The agile S/C provides retargeting at a rate of 4.5º/s with an acceleration of 2.5º/s2; it takes 9 s to slew the S/C over a ground distance of 300 km.

Altitude and Slew Time Altitude and Slew Time
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