WorldView-4 (formerly GeoEye-2)
In June 2014, Digital Globe announced that it received notice from the U.S. Department of Commerce on its application to allow the company to sell its highest-quality and industry-leading commercial satellite imagery. Effective immediately, DigitalGlobe was permitted to offer customers the highest resolution imagery available from their current constellation. Additionally, the updated approvals will permit DigitalGlobe to sell imagery to all of its customers at up to 0.25 m panchromatic and 1.0 m multispectral GSD (Ground Sample Distance) beginning six months after its next satellite WorldView-3 is operational. The launch of Worldview-3 is scheduled for August 2014. 1)
With the launch of WorldView-3, the DigitalGlobe constellation will set a new technological bar for commercial satellite imagery, offering customers the highest available resolution, revisit rate, capacity, and spectral diversity. The company currently operates a fleet of five high-resolution earth imaging satellites. Two of those satellites — GeoEye-1 and WorldView-2 — collect imagery sharper than 0.50 m, and all customers will have access to that imagery at the highest native resolution. WorldView-3 will provide even higher resolution at 0.31 m, and the GeoEye-2 satellite, which is substantially complete, will capture similarly sharp images when it is launched to replace a satellite currently in service or as an expansion to the constellation once warranted by market demand.
WorldView-4 will be DigitalGlobe's next very high resolution imaging satellite providing high resolution and color imagery to commercial, government and international customers. Lockheed Martin is the prime contractor of the WorldView-4 spacecraft. WorldView-4 will provide map-accurate images with a new, high-resolution camera provided by Harris Corporation. In addition to delivering critical geospatial situational awareness and global security information to intelligence analysts, war fighters and decision makers, commercial users will also benefit from access to imagery from WorldView-4. The satellite is fully integrated, tested and ready for launch call-up. 12)
Figure 1: Artist's rendition of the WorldView-4 spacecraft (image credit: Lockheed Martin, Digital Globe)
Table 2: Some spacecraft/observation parameters
Figure 2: Photo of the WorldView-4, the world's second 30 cm imaging satellite, taken in July 2016 (image credit: DigitalGlobe) 13)
• August 15, 2016: WorldView-4, which weighs 2,500 kg and stands 5.5 m tall, is "a big telescope with a little satellite wrapped around it," said Walter Scott, founder, chief technical officer and executive vice president of Westminster, Colorado-based DigitalGlobe. 14)
- WorldView-4 has taken an unusually long time to get to the launch pad. Lockheed Martin began building the satellite, originally named GeoEye-2 for GeoEye of Herndon, Virginia, in 2010. After DigitalGlobe and GeoEye merged in 2013, DigitalGlobe proceeded with its planned launch of WorldView-3 and opted to store GeoEye-2. DigitalGlobe renamed the GeoEye-2 satellite WorldView-4 in 2014 when the company announced its 2016 launch.
Figure 3: Photo of the WorldView-4 spacecraft. Employees at Lockheed Martin completing final preparations of the WorldView-4 imaging satellite (image credit: Lockheed Martin)
• On July 28, 2016, the WorldView-4 satellite arrived at VAFB after a 250-mile trip (from Sunnyvale, CA) in a cleanroom-on-wheels. The Lockheed Martin-built WorldView-4 was transported by truck in a special container that mimics the environment of the cleanroom where the satellite was manufactured. 15)
- Prior to shipping, the satellite passed a full suite of environmental, functional and performance tests and was declared ready for integration with the rocket that will carry it to an altitude of 617 km in space.
Figure 4: Photo of the "cleanroom transport" with WorldView-4 aboard leaving the Lockheed facility in Sunnyvale, CA (image credit: Lockheed)
Launch: The WorldView-4 (former GeoEye-2) spacecraft was launched on November 11, 2016 (18:30 UTC) on an Atlas-V 401 vehicle of ULA (United Launch Alliance) from VAFB, CA, SLC-3E (Space Launch Complex-3East). 16) 17) 18)
The launch of WorldView-4 had to be cancelled on the original launch date of September 18 due to an extremely aggressive fire that consumed some 12,000 acres (4840 hectar) across Vandenberg's South Bases. This was considered to be the largest fire in the base' history but, fortunately, the space launch complexes and other facilities remained clear of the destruction. — All of the 200 miles of cabling have now been certified as in order by the 30th Space Communications Squadron of the US Air Force, and all appears to be a "go" for this delayed and now re-scheduled launch (Ref. 18).
Orbit: Sun-synchronous orbit, altitude = 617 km, inclination = 98º, period = 97 minutes, LTDN (Local equatorial crossing Time on Descending Node) at 10:30 hours, effective revisit time capability ≤ 3 days.
Secondary payloads: 19)
DigitalGlobe has included a CubeSat rideshare program. The CubeSats will be launched by use of ULA's Centaur Aft Bulkhead Carrier that has flown successfully on four previous Atlas V missions. All of the CubeSats manifested for the WorldView-4 mission are sponsored by the U.S. NRO (National Reconnaissance Office) and are unclassified technology demonstration programs. DigitalGlobe is also partnering with California Polytechnic State University, Tyvak Nanosatellite Systems Inc., Lockheed Martin and United Launch Alliance to bring this rideshare program to fruition.
• CELTEE-1 (CubeSat Enhanced Locator Transponder Evaluation Experiment-1), a 1U CubeSat built by M42 Technologies (Seattle,WA) for AFRL (Air Force Research Laboratory).
• Prometheus-2 x 2, two 1.5U technology demonstration CubeSats (Block 2) of LANL (Los Alamos National Laboratory).
• AeroCube-8C and -8D, two 1.5U technology demonstration CubeSats of the Aerospace Corporation (El Segundo, CA) to test electric propulsion, CNT (Carbon Nanotubes) and solar cell technology.
• U2U (Untitled 2U), a 2U CubeSat of AFRL to demonstrate the EGM (Electron and Globalstar Mapping) experiment.
• RAVAN (Radiometer Assessment using Vertically Aligned Nanotubes), a 3U CubeSat mission funded by the NASA and developed and operated by JHU/APL.
The CubeSats will be deployed after WorldView-4 separation as part of the NRO-sponsored ENTERPRISE mission.
Figure 5: Illustration of the deployed WorldView-4 spacecraft (DigitalGlobe)
• February 6, 2017: The WorldView-4 commercial satellite, operated by DigitalGlobe, Inc., has successfully completed on orbit testing and calibration and started to serve the company's first direct access customer on February 1, 2017. 20) 21)
- WorldView-4, launched on November 11, 2016, becomes the fifth active satellite in DigitalGlobe's constellation of high-resolution Earth observation satellites. The satellite's performance meets the industry-leading quality standards of the WorldView fleet and joins WorldView-3 as the world's only commercial satellites capable of achieving 30 cm native resolution. Imagery with this level of detail enables users to reliably read street markings, distinguish between cars, trucks, and vans, and confidently understand activities of significance, as demonstrated by a recent SkyTruth analysis that used WorldView-3 imagery to document the likely transshipment of fish by Southeast Asian vessels in the Indian Ocean.
- The satellite more than doubles DigitalGlobe's capacity to collect 30 cm imagery, enhancing the company's ability to meet the most demanding commercial use cases, such as complementing aerial imagery collection strategies, and enabling the creation of high-quality, imagery-derived products, such as high-resolution 3D models and near-seamless, country-scale basemaps.
Figure 6: Sample image of Brasilia, the Capital of Brazil, acquired with WorldView-4 on January 11, 2017 (image credit: Digital Globe)
Figure 7: Sample WorldView-4 image of Subi Reef, acquired on Dec. 27, 2016 (image credit: DigitalGlobe)
Legend to Figure 7: Subi Reef (also Zhubi Reef) is a reef in the Spratly Islands of the South China Sea located 26 km southwest of Philippine-occupied Thitu Island. It is occupied by China, and claimed by Taiwan, Vietnam, and the Philippines. It currently falls under the jurisdiction of Nansha islands, Sansha city, Hainan province, China. The atoll measures 5.7 km along its longer southwest-northeast axis, and is up to 3.5 km wide. Its total area including the lagoon and rim of the reef measures 16 km2, and the lagoon is up to 22 meters deep. 22)
• December 5, 2016: DigitalGlobe has released the first image from the company's WorldView-4 satellite, launched on Nov. 11, 2016. 23)
Figure 8: WorldView-4's first public image, taken on November 26, 2016, features the Yoyogi National Gymnasium in Shibuya, Tokyo. The site hosted events during the 1964 Olympic Games and will again host international competition when the games return to Tokyo in 2020 (image credit: DigitalGlobe)
• WorldView-4 is the new companion to WorldView-3, effectively doubling the amount of best-on-the-market imagery with unmatched 30 cm resolution. WorldView-3 is booked by U.S. government contracts. WorldView-4 will enable DigitalGlobe sales to foreign allies and commercial uses like agriculture, mining, land developers and oil and gas firms.
Sensor complement: (SpaceViewTM 110)
SpaceViewTM 110 Imaging System:
WorldView-4 will enable expanded capability in the collection of sub-meter imagery to help solve real-world problems. The Harris SpaceView™ line of optical imaging systems offers a broad spectral range of high-resolution optical payloads. The SpaceView™ 110 solution for WorldView-4 will provide the highest resolution satellite imagery commercially available. 24)
The SpaceViewTM 110 payload serves as the imaging payload for DigitalGlobe's WorldView-3 and WorldView-4 satellites. Delivering up to 25 cm panchromatic resolution, SpaceViewTM 110 boasts the most advanced capabilities available from an imaging payload on the market today.
Scanning at 24,000 lines/second, the SpaceView 110 imaging payload is capable of providing an image spanning from London to Paris in just 45 seconds. This feature enables users to understand what is happening over a long distance as soon as possible.
Note: In May 2015, Harris Corp. of Melbourne, FL. acquired ITT Exelis Inc. of Fort Wayne, IN. 25)
ITT Corporation of Rochester, N.Y. received a subcontract from Lockheed Martin Space Systems to continue building the imaging system for GeoEye's next-generation Earth-imaging satellite, GeoEye-2, ITT announced on August 31, 2010. 26)
On March 1, 2011, ITT announced that it has satisfied a key milestone with the successful completion of the CDR (Critical Design Review) for the imaging system for GeoEye-2. 27)
In 2011, ITT Corporation's board of directors approved a plan to separate the company's businesses into three distinct, publicly traded companies. As of Oct. 31, 2011, ITT Exelis is the company involved in C4ISR (Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance) related products and systems and information and technical services. This pertains also to space systems.
In April 2012, ITT Exelis Geospatial Systems has delivered GeoEye's next-generation commercial imaging system for the GeoEye-2 satellite to Lockheed Martin Space Systems Company in Sunnyvale, CA. The instrument provides a GSD (Ground Sample Distance) of 34 cm for panchromatic imagery and 1.36 m for multispectral imagery from an orbit of 681 km. 28)
WorldView-4 will provide map-accurate images with a new, high-resolution camera provided by Harris Corporation. In addition to delivering critical geospatial situational awareness and global security information to intelligence analysts, war fighters and decision makers, commercial users will also benefit from access to imagery from WorldView-4.
WorldView-4 is a multispectral, high-resolution commercial satellite of DigitalGlobe.The SpaceView 110 instrument has a telescope of 1.1 m in diameter ; it will provide imagery of 31 cm in panchromatic resolution and 1.24 m in multispectral resolution from an orbit of 617 km. 29)
Table 3: Parameters of SpaceView 110 on WorldView-4
SpaceView 110 features:
- Industry-leading geolocation accuracy (predicted <4 m CE90 without ground control)
- High capacity in various collection modes
- Bi-directional scanning
- Rapid retargeting using Control Moment Gyros (>2x faster than any competitor) resulting in superior area and point target collection capability
- Direct access tasking from and image transmission to customer sites
- Daily revisit capability.
Figure 9: GSD (Ground Sample Distance) of the SpaceView 110 imager in relation to orbital altitude (image credit: Harris)
Table 4: Overview of the DigitalGlobe constellation 30)
Figure 10: Illustration of the SpaceViewTM 110 instrument (image credit: Harris)
Figure 11: Pictorial view of the DigitalGlobe constellation of high-resolution imagery (image credit: DigitalGlobe)
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14) Debra Werner, "WorldView-4's long road to launch about to pay off for DigitalGlobe," Space News Magazine, August 15, 2016, URL: http://www.spacenewsmag.com/feature/worldview-4s-long-road-to-launch-%E2%80%A8about-to-pay-off-for-digitalglobe/
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21) "WorldView-4 Is Up and Capturing," Satnews Daily, Feb. 6, 2017, URL: http://www.satnews.com/story.php?number=1906185948
24) "SpaceView 110 Satellite Imaging Solution," Harris, URL: https://www.harris.com/sites/default/files/downloads/solutions/55805_sv110-datasheet_final_digital.pdf
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26) "ITT awarded contract to build the Imaging System for the GeoEye-2 Earth-Imaging Satellite," August 31, 2010, URL: http://www.geospatial.itt.com/news/news_100831.shtml
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29) "WorldView-4 Data Sheet," Digital Globe, Nov. 15, 2015, URL: https://dg-cms-uploads-production.s3.amazonaws.com/uploads/document/file/196/DG_WorldView4_DS_11-15_Web.pdf
30) "The DigitalGlobe Constellation," DigitalGlobe brochure, 2016, URL: https://dg-cms-uploads-production.s3.amazonaws.com/uploads/document/file/223/Constellation-Brochure_forWeb.pdf
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 (firstname.lastname@example.org).