WorldView-2 Satellite Sensor - Remote Sensing Tutorial
WorldView-2 Satellite Sensor

DigitalGlobe's WorldView-2 Satellite, launched October 8, 2009, provides 0.5m Panchromatic (B&W) mono and stereo satellite image data. Click here to watch the WorldView-2 launch (courtesy Boeing).

WorldView-2 Satellite Sensor

With its improved agility, WorldView-2 is able to act like a paintbrush, sweeping back and forth to collect very large areas of multispectral imagery in a single pass. WorldView-2 alone is able to collect nearly 1 million km2 every day, doubling the collection capacity of our constellation to nearly 2 million km2 per day. And the combination of WorldView-2’s increased agility and high altitude enables it to typically revisit any place on earth in 1.1 days. When added to the satellite constellation, revisit time drops below one day and never exceeds two days, providing the most same-day passes of any commercial high resolution constellation.

The WorldView-2 sensor provides a high resolution Panchromatic band and eight (8) Multispectral bands; four (4) standard colors (red, green, blue, and near-infrared 1) and four (4) new bands (coastal, yellow, red edge, and near-infrared 2), full-color images for enhanced spectral analysis, mapping and monitoring applications, land-use planning, disaster relief, exploration, defense and intelligence, and visualization and simulation environments.

WorldView-2 Spectral Bands

Coastal Band (400 - 450 nm): This band supports vegetation identification and analysis, and supports bathymetric studies based upon its chlorophyll and water penetration characteristics. Also, this band is subject to atmospheric scattering and will be used to investigate atmospheric correction techniques.

Yellow Band (585 - 625 nm): Used to identify "yellow-ness" characteristics of targets, important for vegetation applications. Also, this band assists in the development of "true-color" hue correction for human vision representation.

Red Edge Band (705 - 745 nm): Aids in the analysis of vegetative condition. Directly related to plant health revealed through chlorophyll production.

Near Infrared 2 Band (860 - 1040 nm): This band overlaps the NIR 1 band but is less affected by atmospheric influence. It supports vegetation analysis and biomass studies.

The WorldView-2 imaging payload is the second such system engineered and manufactured by ITT Space Systems Division for DigitalGlobe. Once deployed, it will operate at an altitude of 770 kilometers, and the advanced on-board imaging system will capture pan-sharpened, multispectral images (with better than 0.5-meter resolution) from almost 500 miles above the Earth. These images supply unprecedented detail and geospatial accuracy, further expanding the applications for satellite imagery in both commercial and government markets. Added spectral diversity provides the ability to perform precise change detection and mapping.

In addition to numerous other technical improvements, WorldView-2 also has the ability to accommodate direct tasking, which will allow select customers around the world to load imaging profiles directly up to the spacecraft and execute delivery of the data directly down to their own ground stations.

WorldView-2 Satellite Sensor Characteristics

Launch Date October 8, 2009
Launch Vehicle Delta 7920 (9 strap-ons)
Launch Site Vandenberg Air Force Base
Orbit Altitude 770 kilometers
Orbit Type Sun synchronous, 10:30 am (LT) descending Node
Orbit Period 100 minutes; 7.25 year mission life, including all consumables and degradables (e.g., propellant)
Spacecraft Size, Mass, & Power 4.3 meters (14 feet) tall x 2.5 meters (8 feet) across, 7.1 meters (23 feet) across the deployed solar arrays; 2800 kilograms (6200 pounds); 3.2 kW solar array, 100 Ahr battery
Sensor Bands Panchromatic
8 Multispectral (4 standard colors: red, blue, green, near-IR), 4 new colors: red edge, coastal, yellow, near-IR2
Sensor Resolution GSD Ground Sample Distance Panchromatic: 0.46 meters GSD at Nadir, 0.52 meters GSD at 20° Off-Nadir

Multispectral: 1.8 meters GSD at Nadir, 2.4 meters GSD at 20° Off-Nadir
(note that imagery must be resampled to 0.5 meters for non-US Government customers)
Dynamic Range 11-bits per pixel
Time Delay Integration (TDI) Panchromatic - 6 selectable levels from 8 to 64
Multispectral - 7 selectable levels from 3 to 24
Swath Width 16.4 kilometers at nadir
Attitude Determination and Control 3-axis stabilized
Actuators Control Moment Gyros (CMGs)
Sensors Star trackers, solid state IRU
GPS Position Accuracy & Knowledge < 500 meters at image start and stop
Knowledge: Supports geolocation accuracy below Retargeting
Agility Acceleration 1.5 deg/s/s
Rate: 3.5 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 = 1355 km wide swath
Higher angles selectively available
Per Orbit Collection: 524 gigabits
Max Contiguous Area Collected in a Single Pass: 96 x 110 km mono, 48 x 110 km stereo
Revisit Frequency 1.1 days at 1 meter GSD or less 3.7 days at 20° off-nadir or less (0.52 meter GSD)
Geolocation Accuracy (CE 90) Specification of 12.2m CE90, with predicted performance in the range of 4.6 to 10.7 meters (15 to 35 feet) CE90, excluding terrain and off-nadir effects

With registration to GCP's in image: <2.0 meters (6.6 ft)

DigitalGlobe currently operates the QuickBird satellite, which can collect black-and-white, or panchromatic, images with 0.61-meter resolution at Nadir. The satellite, launched in October 2001, also collects multispectral images with 2.5 meter resolution. WorldView-1 high-capacity, panchromatic imaging system features half-meter resolution imagery. Operating at an altitude of 496 kilometers, WorldView-1 has an average revisit time of 1.7 days and is capable of collecting up to 750,000 square kilometers (290,000 square miles) per day of half-meter imagery. The satellite also is equipped with state-of-the-art geo-location accuracy of <2m without GCP's while with one (1) or two (2) GCP's the geospatial accuracy is <1m and further exhibits stunning agility with rapid targeting and efficient in-track stereo collection.