LOS ANGELES Aug 28 (Reuters) - An unmanned Delta 4-Heavy rocket, the largest in the U.S. fleet, blasted off from Vandenberg Air Force Base in California on Wednesday to put a classified spy satellite into orbit for the National Reconnaissance Office, officials said Wednesday.
The 23-story-tall rocket lifted off at 11:03 a.m. local time/1803 GMT from a launch pad originally built for, but never used by, NASA's now-retired space shuttles.
No details about the rocket's spy-satellite payload were released.
With three main booster-rocket cores, the Delta 4-Heavy is capable of putting a satellite the size of school bus into an orbit around Earth's poles.
Wednesday's launch was the second Delta 4-Heavy to fly from California. The rocket, built by United Launch Alliance, a partnership of Boeing Co. and Lockheed Martin Corp. , also has flown five times from Cape Canaveral Air Force Station in Florida.
"We are truly honored to deliver this critical asset to orbit," United Launch Alliance vice president Jim Sponnick said in a statement, praising the groups involved in the launch effort.