WorldView-2 Overview - Remote Sensing Satellite Image Tutorial
WorldView-2 Overview

WorldView-2, launched October 2009, is the first high-resolution 8-band multispectral commercial satellite. Operating at an altitude of 770 kilometers, WorldView-2 provides 46 cm* panchromatic resolution and 1.85 meter* multispectral resolution. WorldView-2 has an average revisit time of 1.1 days and is capable of collecting up to 785,000 square kilometers (303,000 square miles) of 8-band imagery per day, greatly enhancing the DigitalGlobe multispectral collection capacity for more rapid and reliable collection.

The WorldView-2 system, offering incredible accuracy, agility, capacity and spectral diversity, allows DigitalGlobe to substantially expand its imagery product offerings to both commercial and government customers.

Features

Benefits

Very high resolution

  • 46 cm* panchromatic at nadir
  • 52 cm out to 20 off-nadir

Provides highly detailed imagery for precise map creation, change detection and in-depth image analysis (note that imagery must be re-sampled to 50 cm for non-US Government customers)

The most spectral diversity commercially available

  • 1.85 m* resolution at nadir
  • 4 standard colors: blue, green, red, near-IR 1
  • 4 new colors: coastal, yellow, red edge, near-IR 2

Provides the ability to perform precise change detection and mapping at unprecedented resolutions in multispectral imagery, and opens door to creation of numerous new products

Industry-leading geolocation accuracy

  • Ultra-stable platform, high-precision attitude sensors and GPS

Allows the creation of accurate maps in remote areas, maximizing the utility of whatever resources are available:

  • Geolocation Accuracy specification of 6.5 m 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 GCPs in image: 2.0 meters (6.6 feet) CE90

High capacity over a broad range of collection types

  • 16.4 km width imaging swath (wider than any competitor)
  • Bi-directional scanning
  • Rapid retargeting using Control Moment Gyros (>2x faster than any competitor)
  • 2199 gigabits on-board storage
  • 800 Mbps X-band data downlink

Collects, stores and downlinks a greater supply of frequently updated global imagery products than competitive systems

  • DigitalGlobe ImageLibrary filled with unrivaled speed
  • Broadest range of collection sizes, without sacrificing capacity from small points to long strips and large areas
  • Stereoscopic areas on a single pass, ensuring image continuity and consistency of quality

Direct downlink to customer sites available using same high-speed 800 Mbps X-band downlink

Expedites image processing and delivery to customers where speed is a driving factor

World-class telescope

  • High contrast (MTF) and signal to noise ratio
  • Selectable Time Delay Integration (TDI) levels, both panchromatic and mutlispectral bands
  • 11-bit dynamic range

Extends the range of suitable imaging collection targets and enhances image interpretability

Frequent revisits at high resolution enabled by higher altitude

  • 1.1 days at 1 m GSD or less
  • 3.7 days at 20 off-nadir or less (52 cm GSD)

Frequent revisits increase image collection opportunities, enhance change detection applications and enable accurate map updates

Design and Specifications

Launch Information

Date: October 8, 2009
Launch Vehicle: Delta 7920 (9 strap-ons)
Launch Site: Vandenberg Air Force Base, California

Orbit

Altitude: 770 kilometers
Type: Sun synchronous, 10:30 am descending node
Period: 100 minutes

Mission Life

7.25 years, including all consumables and degradables
(e.g. propellant)

Spacecraft Size, Mass and 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: 450 - 800 nm
  • 8 Multispectral:
    • Coastal: 400 - 450 nm
    • Blue: 450 - 510 nm
    • Green: 510 - 580 nm
    • Yellow: 585 - 625 nm
    • Red: 630 - 690 nm
    • Red Edge: 705 - 745 nm
    • Near-IR1: 770 - 895 nm
    • Near-IR2: 860 - 1040 nm

Sensor Resolution (GSD = Ground Sample Distance)

  • Panchromatic:
    • 46 cm GSD at nadir*
    • 52 cm GSD at 20 off-nadir
  • Multispectral:
    • 1.85 m GSD at nadir*
    • 2.07 m GSD at 20 off-nadir

Dynamic Range

11-bits per pixel

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

Pointing Accuracy and Knowledge

Accuracy: < 500 meters at image start and stop
Knowledge: Supports geolocation accuracy below

Retargeting Agility

Acceleration: 1.43 deg/s/s
Rate: 3.86 deg/s
Time to Slew: 200 kilometers: 10 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 +/-45 off-nadir = 1651 km wide swath
Higher angles selectively available

Max Contiguous Area
Collected in a Single Pass
(30 off-nadir angle)

Mono: 138 x 112 km (8 strips)
Stereo: 63 x 112 km (4 pairs)

Revisit Frequency
(at 40N Latitude)

1.1 days at 1 meter GSD or less
3.7 days at 20 off-nadir or less (0.52 meter GSD)

Geolocation Accuracy (CE90)

Specification of 6.5 m CE90, with predicted performance in the range of 4.6 to 10.7 m (15 to 35 feet) CE90, excluding terrain and off-nadir effects

With registration to GCPs in image : 2.0 m (6.6 feet)

Source: http://www.digitalglobe.com