File photo of Delta 2 rocket on the launch pad at Cape Canaveral. Photo: NASA-KSC

Deployment of the next Global Positioning System satellite by a Boeing Delta 2 rocket is being delayed at least a month while the Air Force reviews new changes to the launcher's self-destruct system.

Liftoff of the three-stage rocket and the GPS 2R-8 military navigation spacecraft from Complex 17 at Cape Canaveral Air Force Station in Florida was scheduled for May 8. A new launch date has not been established.

"The Air Force anticipates that the upcoming Delta 2 GPS 2R-8 mission will slip a minimum of one month," Lt. Col. Nancy Insprucker, the Air Force's acting deputy launch programs director, said in a written statement.

"This decision was made after assessing the installation procedures of a new Delta 2 Automatic Destruct System (ADS) upgrade, which is used by Range Safety to destruct the booster should it veer off course during a launch."

"Everyone wanted to take a little extra time to ensure all the implementation procedures and the like, as well as...the design itself, was appropriate and have another review of it. We have no problem with that at all," Jay Witzling, Boeing vice president and deputy Delta program manager, said in an interview Wednesday.

"The processing of the vehicle for GPS and the scheduling is pretty much controlled by the Air Force," Witzling added.

The destruct system is triggered to destroy the rocket and break up the pieces to ensure all the wreckage falls within designated safety zones in the event of a malfunction during launch.

But during analysis in preparation for launching NASA's Space Infrared Telescope Facility aboard the first Delta 2-Heavy rocket next January, which will use the larger strap-on solid motors developed for the Delta 3, engineers uncovered a possible scenario where the current destruct system was lacking.

"The current ADS configuration works very well," Insprucker said. "However, during a recent analysis, Boeing discovered a new failure mode that was not covered by the existing ADS design. While the odds of this particular scenario occurring are extremely low, Boeing shared it with Range Safety and designed an ADS upgrade to address it.

"The upgraded design addresses a premature fairing separation combined with fairing damage to the command destruct system within the second stage," Insprucker said.

"The current and the upgraded system apply to all three stages and the nine strap-on Graphite Epoxy Motors. The current ADS has a lanyard that routes from the engine section at the base of the vehicle to the top of the interstage -- this lanyard does not cross the separation plane between stages 1 and 2. The ADS upgrade will extend the current ADS lanyard through the second stage mini-skirt to the payload fairing and cross the separation plane between stages 1 and 2.

"Boeing is also adding cable cutters to sever the lanyard connection at the top of the interstage. This will occur immediately prior to normal separation and disarm the ADS upgrade during normal flights," Insprucker explained.

The destruct system upgrade will actually fly for the first time on May 2 when a Delta 2 rocket is launched from Vandenberg Air Force Base in California carrying NASA's Aqua Earth observing satellite.

NASA Launch Manager Chuck Dovale said in an interview Wednesday that the space agency had thoroughly reviewed the new system and was comfortable proceeding with the launch.

"Initially it was a constraint to putting the vehicle up (on the pad). We cleared that hurdle. Then it was a constraint to putting the spacecraft up and we cleared that hurdle."

The Aqua satellite was delivered to the pad Wednesday and hoisted atop the Delta for mating.

"Like any system that you change to the rocket you just want to make sure you have done it correctly. Eventually, this will be a production change to the vehicle and won't be a field installation...You don't like to do that kind of work in the field if you don't have to," Witzling said.