Figure 1 Boeing Delta 2 rocket with WorldView-1 satellite on board shoots skyward on Sept. 18.
Half-Meter Imagery Coming Mid-October
The Sept. 18 launch of DigitalGlobe's next-generation WorldView-1 satellite from Vandenberg Air Force Base rocketed the Colorado company's status as a world leader in the capture of high resolution Earth imagery to a new height. The deployment was the first of two launches that have been planned a year apart as part of a campaign to maintain simultaneously three high-resolution DigitalGlobe imaging birds in Low Earth Orbit.
Equipped with ITT Corporation's .5-meter resolution panchromatic sensors, WorldView-1 will be capable of collecting up to 750,000 square kilometers of images per day, with a revisit time of 1.7 days. The bulk of its capacity has been reserved by the National Geospatial-Intelligence Agency (NGA) for use in its NextView national security program, but most of these detailed images also will be available commercially from the DigitalGlobe ImageLibrary.
WorldView-1 joins the company's current orbiting satellite, QuickBird, at a time when the commercial demand for high-resolution Earth imagery is beginning to generate some real mass. Launched in October of 2001, Quickbird, at .6-meter panchromatic and 2.4-meter multispectral resolutions, will now be free to task for the commercial market. Still, DigitalGlobe will not reach the apogee of its corporate objective—a daily collection capacity of one million square kilometers—until it shoots its second next-generation vessel, WorldView-2, into space late next year. That privately-underwritten satellite will be able to image in eight multispectral bands at 1.8 meters.
Quickbird has remained the world's highest-resolution imaging satellite since its debut six years ago.
Yet its capabilities will be surpassed next year when GeoEye (Dulles, Va.) positions its own next-generation bird in the heavens. GeoEye-1 will be fitted with 1.65-meter multispectral hardware, and, like WorldView-1, it will dedicate its tasks mostly to the NGA nat-ional security contract. Mark Brender of GeoEye stated, "This launch is important not only to DigitalGlobe but for our entire industry. Both commercial remote sensing companies must succeed in launching next-generation imaging systems, and we are next up with the launch of GeoEye-1 in the first part of 2008."
So market forces continue to choreo-graph the competitive dance of 21st Century imaging from the near reaches of space. Ultimately, though, the projected life of a satellite and technology's arrival at the lowest common denominator of practicable resolution appear to trump the efforts of one vendor to outrace his competitor to the next milestone. A case in point is DigitalGlobe, whose constellation of three satellites may be short-lived, considering that QuickBird's operational lifespan is not expected to last beyond 2009. It is factors like this that tend to level the playing field to a less variable grade. Geobrowser suppliers, software dev-elopers and any number of other original equipment manufacturers are continuing to seed the commercial demand for Earth imagery to a degree that renders almost academic the debate over who can claim title to being the lead supplier.
This kind of reality does nothing to diminish the mollifying beauty of a pristine launch. WorldView-1 is the second commercial bird to enter orbit on a Boeing Delta 2 rocket under the auspices of the United Launch Alliance, a joint venture between Boeing and Lockheed Martin. Built by Ball Aerospace & Technologies Corporation (Broomfield, Colo.), the satellite blasted toward the ionosphere at 11:35 a.m. PDT on Sept. 18 in an orange explosion of liquid oxygen, carrying its payload of 2,500 kilograms. There were no adverse events.
The craft reached Mach 1 and jettisoned the first of its solid propellants, and then its airlift solids. At 4:20 minutes, its main engines cut off, and following second-stage separation, its protective faring separated and sloughed off. It jettisoned more solid motors under normal disturbance. At 50 nautical miles it approached 8,200 miles per hour. Its main engine cutoff at the ionosphere exploded in a starburst, followed by another explosion with the second stage ignition and additional propellant jettisoning. After several minutes, WorldView-1 had reached a speed in excess of 13,000 miles per hour as it approached its rendezvous with a targeted 496-kilometer sun-synchronous orbit.
Though American and European vendors appear to jockey tirelessly for market position, a point of diminishing return for image resolution does exist from technical and legal perspectives. Both panchromatic and multispectral imagery have secure places reserved in the scheme of national security objectives, and according to Chuck Herring, DigitalGlobe's Director of Corporate Communications, the half-meter benchmark is as close as any modern sensor needs to see, as a practical consideration.
"The resolution of .5 meters is the best we can provide to commercial customers," he said in a recent communication. "So for the foreseeable future, we plan to have our satellites provide the half-meter resolution imagery. If you have your satellite provide higher resolution, you collect less imagery."
Moreover, security-driven government restrictions prevent commercial suppliers and buyers from entering this realm. If a company did improve its resolution to a quarter meter, Herring said, it would have to resample the imagery to half meter for every non-governmental buyer.
But WorldView-1 is more than just hawk-eyed. It is also the most nimble imaging satellite ever launched. The bird sports state-of-the-art geolocation accuracy, stunning agility and in-track stereo collection. Herring explained that the latter two features allow WorldView-1 to collect its tasked images with a minimum of flyovers. "Many customers need to have several point targets within an area collected," he said. "With current generation satellites, this may take several passes. With Worldview-1, we are able to collect five to ten times more point targets because the satellite is so agile and we are able to point at rapid rates."
First images are due back in mid-October. Herring would not say whether Digital-Globe has struck any large commercial deals with major customers such as Google outside of the NGA contract, but did acknowledge that "they are always interested in more capabilities and capacity."
All else being equal, WorldView-1's launch marks, at minimum, the arrival of geospatial data collection at state-of-the art metrics for applications in the mapping and monitoring markets.