Minimize WorldView-3

WorldView-3 (WV-3)

WorldView-3 is a next generation commercial imaging mission of DigitalGlobe Inc., Longmont, CO, USA. With the addition of WV-3 to its satellite constellation (in addition to QuickBird, WorldView-1 and WorldView-2), DigitalGlobe will be capable of collecting ~1 billion km2 of Earth imagery per year.

In August 2010, DigitalGlobe was awarded an SLA (Service Level Agreement) with NGA (National Geospatial-Intelligence Agency) within its Enhanced View program. The contract deals with the purchase of satellite imagery and includes also an NGA cost share for the development and launch of the WorldView-3 spacecraft. DigitalGlobe plans a launch of WorldView-3 for the end of 2014. 1)

DigitalGlobe is adding a SWIR (Shortwave Infrared) sensing capability (8-band instrument) to its planned WorldView-3 satellite that will open up a host of new civil and military applications. 2) 3)

WorldView-3 provides 31 cm panchromatic resolution, 1.24 m MS (Multispectral) resolution, 3.7 m SWIR (Short-Wave Infrared) resolution, and 30 m CAVIS (Clouds, Aerosols, Vapors, Ice, and Snow) resolution. CAVIS will monitor the atmosphere and provide correction data to improve WorldView-3's imagery when it images earth objects through haze, soot, dust or other obscurants. WorldView-3 has an average revisit time of < 1 day and is capable of collecting up to 680,000 km2 per day, further enhancing the DigitalGlobe collection capacity for more rapid and reliable collection. 4) 5)

WorldView3_Auto2

Figure 1: Artist's rendition of the deployed WorldView-3 spacecraft in orbit (image credit: DigitalGlobe)

 

 

Spacecraft:

On August 30, 2010, DigitalGlobe awarded contracts to BATC (Ball Aerospace & Technologies Corporation) and to ITT Industries to build the WorldView-3 spacecraft and imager, respectively. 6) 7) 8) 9)

The BCP 5000 bus is being used for the WorldView-3 spacecraft. The high-performance BCP 5000 has a design life of more than seven years, and provides a platform with increased power, resolution, agility, target selection, flexibility, transmission capability and data storage. Ball provided the BCP 5000 under a fixed-price contract.

WorldView-3 builds upon WorldView-2 and WorldView-1 technology by carrying forward the satellites' advanced CMGs (Control Moment Gyroscopes). The CMGs, developed at BATC, reorient a satellite over a desired collection area in 4-5 seconds, compared to 30-45 seconds needed for traditional reaction wheels.

WorldView3_Auto1

Figure 2: Ball Aerospace engineers install an advanced Control Moment Gyroscope into WorldView-3 (image credit: BATC)

 

Spacecraft size

5.7 m tall x 2.5 m across; 7.1 m across with the solar panels deployed

Spacecraft mass

2800 kg

Spacecraft power

3.1 kW solar array, 100 Ahr battery

Design life

7.25 years, estimated service life: 10 to 12 years

ADCS (Attitude Determination and Control Subsystem)

- Type: 3-axis stabilized
- Actuators: CMGs (Control Moment Gyros)
- Sensors: Star trackers, precision IRU, GPS receiver

Spacecraft pointing

- Accuracy: < 500 m at image start/stop; Knowledge: Supports geolocation accuracy
- Geolocation accuracy: Predicted < 3.5 m CE90 without ground control

Retargeting agility

Time to slew 200 km: 12 s

Onboard data storage

2.199 Tbit solid state memory with EDAC

RF communications

Image & ancillary data: 800 and 1200 Mbit/s, X-band
Housekeeping data rates: 4, 16, 32, or 64 kbit/s real-time; 524 kbit/s stored, X-band
Command data rates: 2 or 64 kbit/s, S-band

Table 1: Overview of spacecraft parameters

WorldView3_Auto0

Figure 3: Photo of the WorldView-3 spacecraft during AIT (Assembly, Integration and Test) phase at BATC (image credit: BATC) 10)

In January 2014, BATC has completed integration of the WorldView-3 spacecraft. With the imagery sensor and associated electronics now integrated, the completed satellite bus is ready for system-level performance testing, followed by thermal vacuum and environmental testing.

Orbit: Sun-synchronous orbit, altitude = 617 km, inclination = 98º, LTDN (Local Time on Descending Node) = 13:30 hours, period = 97 minutes.

 

Launch: WorldView-3 is ready for launch in mid-2014 on an Atlas-V vehicle of LMCLS (Lockheed Martin Commercial Launch Services) from VAFB, CA.

Note: DigitalGlobe and GeoEye merged on January 31, 2013 to become one company, DigitalGlobe. On February 4, 2013, DigitalGlobe announced that its previously planned satellite construction program related to its third WorldView-class satellite remains on track. 11)

• DigitalGlobe can now confirm that it plans to complete WorldView-3 on its original schedule to be ready for launch in mid-2014 in order to meet the requirements of its EnhancedView contract with the U.S. government. That contract calls for completion and launch of WorldView-3, which will offer the most spectral diversity available commercially and be the first to offer multiple Short-Wave Infrared bands that allow for accurate imaging through haze, fog, dust, smoke and other air-born particulates. DigitalGlobe's largest customer, NGA (National Geospatial-Intelligence Agency), has confirmed the requirements of DigitalGlobe's EnhancedView contract remain unchanged.

• Accordingly, following its just completed combination with GeoEye, DigitalGlobe intends to complete the construction of GeoEye-2 in 2013 and to preserve it as a ground spare to meet customer demand or as a replacement for other on-orbit satellites. Previously, GeoEye had expected to launch GeoEye-2 in 2013 (Ref. 11).

 


 

Sensor complement: (WV-3 Imager, CAVIS)

The WV-3 Imager, including the SWIR sensor and optics, was designed and built by ITT Exelis.

- In September 2010, Exelis was selected to build the imaging system, which will include a sensor subsystem and an optical telescope unit, for DigitalGlobe's WorldView-3 spacecraft.

- The CDR (Critical Design Review) for the imaging payload of WorldView-3 was completed on April 14, 2011.

- In Sept. 2013, Exelis delivered an integrated, super-spectral payload consisting of a telescope, sensor and shortwave infrared system for the WorldView-3 satellite. 12)

Note: On October 31, 2011, ITT Corporation spun off its defense and water technology businesses to form three separate, publically-traded companies: 13)

1) Xylem Inc., a water technology and services company headquartered in White Plains, NY.

2) Exelis Inc. (or ITT Exelis), a defense technology business headquartered in Tysons Corner, VA. ITT Exelis Geospatial Systems of Rochester, N.Y., is supplying the sensor complement of WorldView-3.

3) ITT Corporation, a global manufacturing company headquartered in White Plains, NY.

Exelis has designed and built imaging systems for each of DigitalGlobe’s current satellite constellation, including WorldView-1, WorldView-2, Ikonos-2, GeoEye-1, GeoEye-2 and QuickBird.

WorldView-3 combines the most productive high resolution commercial sensor subsystem available with a highly accurate and stable optical telescope unit. In addition of offering 0.31 m resolution panchromatic and 8-band MS imagery, WorldView -3 was licensed by NOAA to collect 8-band SWIR (Shortwave Infrared) imagery. This will make DigitalGlobe the only company with multiband SWIR capabilities, greatly expanding the range of customer applications enabled by the DigitalGlobe constellation. 14) 15)

Spectral range

Band name

Spectral band

GSD (Ground Sample Distance)

Panchromatic band (1)

450 - 800 nm

Nadir: 0.31 m, 20º off-nadir: 0.34 m

MS (Multispectral) bands (8) in VNIR (Visible Near Infrared)

Coastal

400 - 450 nm

Nadir: 1.24 m
20º off-nadir: 1.38 m

Blue

450 - 510 nm

Green

510 - 580 nm

Yellow

585 - 625 nm

Red

630 - 690 nm

Red egde

705 - 745 nm

Near-IR1

770 - 895 nm

Near-IR2

860 - 1040 nm

Multiband (8 bands) in SWIR (Shortwave Infrared) spectral range

SWIR-1

1195 - 1225 nm

Nadir: 3.70 m
20º off-nadir: 4.10 m

SWIR-2

1550 - 1590 nm

SWIR-3

1640 - 1680 nm

SWIR-4

1710 - 1750 nm

SWIR-5

2145 - 2185 nm

SWIR-6

2185 - 2225 nm

SWIR-7

2235 - 2285 nm

SWIR-8

2295 - 2365 nm

 

 

 

 

CAVIS bands (12)
CAVIS (corrects for Clouds, Aerosols, Vapors, Ice, and Snow)

Desert clouds

405 - 420 nm

Nadir: 30 m

Aerosols-1

459 - 509 nm

Green

525 - 585 nm

Aerosols-2

620 - 670 nm

Water-1

845 - 885 nm

Water-2

897 - 927 nm

Water-3

930 - 965 nm

NDVI-SWIR

1220 - 1252 nm

Cirrus

1350 - 1410 nm

Snow

1620 - 1680 nm

Aerosol-3

2105 - 2245 nm

Aerosol-3

2105 - 2245 nm

Data quantization

11 bit/pixel Pan and MS; 14 bit/pixel SWIR

Swath width

13.1 km

Revisit frequency
(at 40º N latitude)

1 m GSD: < 1.0 day
4.5 days at 20° off-nadir or less

Geolocation accuracy

< 3.0 m CE90 (Circular Error of 90%)

Table 2: Specification of the WorldView-3 imagers (Ref. 4)

CAVIS ( Clouds, Aerosols, Vapors, Ice, and Snow): The CAVIS imager is provided by BATC. The objective of CAVIS is to monitor the atmosphere and provide correction data to improve WorldView-3's high-resolution imagery when it images Earth objects through haze, soot, dust or other obscurants.

 


1) “DigitalGlobe Secures $3.55 Billion EnhancedView Agreement with National Geospatial Intelligence Agency (NGA),” August, 9, 2010, URL: http://media.digitalglobe.com/index.php?s=43&item=225

2) Warren Fester, “DigitalGlobe Adding Infrared Capability to WorldView-3 Satellite,” Space News, April 17, 2012, URL: http://spacenews.com/earth_observation/120417-digitalglobe-adding-ir-worldview3.html

3) “DigitalGlobe Unveils New Details of WorldView-3 Satellite,” Space Daily, April 24, 2012, URL: http://www.spacedaily.com/reports/DigitalGlobe_Unveils_New_Details_of_WorldView_3_Satellite_999.html

4) WorldView-3,” DigitalGlobe Data Sheet, URL: http://www.digitalglobe.com/downloads/WorldView3-DS-WV3-Web.pdf

5) “WorldView-3 Satellite Sensor,” Satellite Imaging Corporation, URL: http://www.satimagingcorp.com/satellite-sensors/worldview-3.html

6) “Ball Aerospace and ITT Corporation to Construct Company’s Fourth Digital Imagery Satellite,” August 30, 2010, URL: http://media.digitalglobe.com/index.php?s=43&item=228

7) Peter B. de Selding, “DigitalGlobe Awards $307 M in Contracts for WorldView-3 Satellite,” Space News, Sept. 6, 2010, p. 6

8) “Ball Aerospace Begins Integration Phase for DigitalGlobe's WorldView-3 Satellite,” BATC News Release, April 8, 2013, URL: http://www.ballaerospace.com/page.jsp?page=30&id=525

9) http://www.ballaerospace.com/page.jsp?page=294

10) “Ball Aerospace Completes Integration of WorldView-3 Spacecraft,” PR Newswire, Jan. 27, 2014, URL: http://www.prnewswire.com/news-releases/ball-aerospace-completes-integration-of-worldview-3-spacecraft-242192151.html

11) “DigitalGlobe's WorldView-3 Satellite Continues on Track for Mid-2014 Launch - Company Will Complete GeoEye-2 Satellite to Preserve as Ground Spare,” DigitalGlobe Press Release, Feb. 4, 2013, URL: http://investor.digitalglobe.com/phoenix.zhtml?c=70788&p=irol-newsArticle&ID=1781079&highlight=

12) “Exelis delivers first-of-its-kind commercial payload to DigitalGlobe for WorldView-3 satellite,” Exelis, Sept. 10, 2013, URL: http://www.exelisinc.com/news/pressreleases/Pages/Exelis-delivers-first-of-its-kind-commercial-payload-to-DigitalGlobe-for-WorldView-3-satellite.aspx

13) Irene Lockwood, “ITT’s Commercial Imaging Payload Passes Major Milestone,” ITT Press Release, April 14, 2011, URL: http://www.exelisinc.com/news/pressreleases/Documents/Archived%20Press%20Releases/2011/news_2011-04-14.pdf

14) http://www.satimagingcorp.com/satellite-sensors/WorldView3-DS-WV3-Web.pdf

15) Fred A. Kruse, Sandra L. Perry, “Mineral Mapping Using Simulated Worldview-3 Short-Wave-Infrared Imagery,” Remote Sensing, 2013, Vol. 5, pp. 2688-2703, doi:10.3390/rs5062688, URL: http://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDgQFjAB&url=http%3A
%2F%2Fwww.mdpi.com%2F2072-4292%2F5%2F6%2F2688%2Fpdf&ei=OJ8UU4SuMoTItQa8ooAo&usg
=AFQjCNFPYLlPmikXyu_h9h5rrqCoaYMkbw&bvm=bv.61965928,d.Yms



The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates.