WASHINGTON — Boeing’s scheduled June 27 launch of a classified U.S. government satellite will mark the first West Coast mission for its Delta 4 rocket.

That launch will take place from a facility at Vandenberg Air Force Base in California that originally was intended to serve as a West Coast launch pad for NASA’s space shuttle, according to Byron Wood, president of Pratt & Whitney Rocketdyne, which built two of the engines that will carry the Delta 4 into space.

The launch also will mark the first launch of a National Reconnaissance Office (NRO) payload aboard a Delta 4, according to Dan Collins, Boeing vice president of expendable launch systems. Collins declined to discuss the details of the payload or its planned orbit, but noted that Vandenberg Air Force Base is generally used to place satellites in polar orbits.

“To us, it’s really a culmination to a commitment made long ago to the Air Force to deliver a fully capable launch family with the Delta 4,” Collins said in a June 20 interview.

The launch of the satellite, known only as NROL-22, had been scheduled for early 2005, but was delayed at the government’s request, Collins said.

The rocket that will launch NROL-22 is a Delta 4 Medium+ (4,2), meaning that it features an upper stage that is four meters in diameter, with a single core booster augmented by two solid-rocket motors, Collins said.

That configuration was used to launch a geostationary weather satellite from Cape Canaveral, Fla., for the National Oceanic and Atmospheric Administration last month, as well as the inaugural Delta 4 launch, which placed a commercial telecommunications spacecraft in orbit in late 2002, Collins said.

Vandenberg’s Space Launch Complex-6 was built in the 1980s when the U.S. Department of Defense was planning to use space shuttles for military launches from the West Coast, Wood said in a June 21 interview. However, the Air Force canceled plans to use the site for shuttle launches after the Challenger disaster, said Wood, who was managing Rocketdyne’s space shuttle main engine program at the time.

The site was later used to launch Lockheed Martin Corp.’s Athena rocket in the 1990s before it was turned over to Boeing in 1999 for modification to handle the Delta 4 rockets.

The next West Coast launch for the Delta 4 is expected to be a Defense Meteorological Satellite Program spacecraft for the Air Force in November, followed by NROL-25 in summer 2007, according to Doug Shores, a Boeing spokesman.

In addition to the medium-lift rocket that will launch NROL-22, the Delta 4 line also includes a heavy-lift variant.

That rocket failed to put its payload into a useable orbit during a demonstration launch in December 2004.

Boeing has since resolved the issues that caused the sensors in the rocket’s fuel tank to shut down prematurely, but the first operational launches with the heavy-lift vehicle will not take place before 2007 at the instance of the payload customers, Collins said.

That demonstration was expected to be followed by the launch of a Defense Support Program missile warning satellite in August 2005, as well as NROL-26 in December 2005.

The NRO is waiting to see if the Delta 4 heavy is successful in launching the missile warning satellite in early 2007 before it sets a date for its satellite, according to Rick Oborn, an NRO spokesman. If that launch is successful, the NRO satellite would likely follow several months later, he said.