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19-Sep-07 | Delta flight 326 – WorldView 1

On Tuesday, 18 September 2007, a two-stage Delta II launched WorldView 1 for the DigitalGlobe system.

The United Launch Alliance flight team produced yet another flawless countdown, with no apparent issues to address. Upper level winds, initially a concern, improved throughout the morning and were not a factor.

The Delta 7920 model, flying with a 10-foot-diameter composite fairing, leapt off the pad at SLC-2W at the opening of its fourteen-minute window, at an official range liftoff time of 11:35:00.526 PDT. As is typical for Delta II launches from Vandenberg, the vehicle retained its ground-lit solid boosters for more than 20 seconds after burn-out in order to avoid dropping them near off-shore oil platforms; a dog-leg manoeuvre was also included in the flight profile to correct for a path that initially aimed toward the southwest, for similar safety reasons.

Following first and second stage burns and an approximately 43.5-minute coast phase, the second stage relit for a brief orbit adjustment, then imparted a gentle spin to the spacecraft for stabilization prior to release into a nearly-circular polar orbit, about 270 nautical miles in altitude. (For a complete play-by-play, check out Justin Ray’s always informative Mission Status Report at

WorldView 1 is a new commercial imaging satellite with impressive capabilities, not least of which is half-meter resolution. From its polar orbit it will be able to image any point on Earth with an average revisit time of 1.7 days, and its high-capacity on-board memory can store up to 290,000 square miles of half-meter imagery per day. Given its potential for intelligence gathering, it comes as no surprise that the U.S. government is already signed on as a customer. WorldView’s predecessor, Quickbird 2, also launched on a Delta II in 2001.

The flight, the 130th for Delta II since its debut in 1989, set a new all-time record for consecutive launch successes at 75. Previously, the Delta II had been tied with the Ariane 4, which saw its final launch in 2003.

Many people involved with Tuesday’s launch had strongly positive words for Delta II reliability, including Kris Walsh, United Launch Alliance’s director of NASA and commercial programs for Delta, who said, “It’s a great little rocket. I’ll continue to fly it as long as I can.” Nevertheless, with the U.S. Air Force moving to the larger Delta IV and NASA uncertain about maintaining the Delta II infrastructure by itself, the production line is shutting down, and only 25 vehicles remain to be flown.

Close observers of the Delta II may have noticed that the Delta insignia on the vehicle no longer includes the stars signifying consecutive successes (as detailed in the FAQ), something that has been eliminated since ULA began managing launches. Perhaps someone realised how cluttered 75 stars can be! (Kudos and congratulations to everyone at ULA for this “stellar” record… pardon the pun.) -ed.

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