The Boeing Delta 2 rocket is stacked on launch pad 17B for the GPS 2R-8 mission. Photo: Justin Ray/Spaceflight Now

The next launch of a replacement Global Positioning System military satellite aboard a Boeing Delta 2 rocket, once envisioned to occur in mid-August, has been postponed while engineers study wiring harnesses in the Delta fleet.

Concerns were raised after a problem was uncovered with wiring for a different rocket in Boeing's Alabama manufacturing plant.

"The cause of concern is abrasions to wire found when Boeing conducted a high voltage resistance (meggar) check of s similar Delta 4 harness at its factory in Decatur, Ala. The concern is a precautionary evaluation of harnesses for Delta 2 vehicles processed to date," the Air Force said in a written statement.

Officials say the issue only involves a handful of Delta 2 rockets.

There are wiring harnesses in all the various segments of each vehicle, and the ongoing investigation is aimed at determining the extent of the concern. Engineers are also trying to find out what might happen if a wiring short occurred during launch.

"The concern is the potential for a short on a mission critical wire harness, possibly causing mission failure. At this point, the team is investigating the individual wire harnesses to determine possible failure modes, their statistical probability, and the corresponding severity of those possible failures," the statement said.

"Boeing and the Air Force are conducting a thorough investigation into the root cause of wire damage, and the time period the damage could have occurred. An assessment of the vulnerability to a short circuit on each wire harness is also being conducted. The Air Force will take whatever time is necessary to ensure mission success."

A new launch date has not been set.

This launch will boost the GPS 2R-8 spacecraft into Earth orbit from launch pad 17B at Cape Canaveral, Florida. The Lockheed Martin-made GPS satellite is the next in a series of spacecraft built to replenish the military navigation system. The GPS constellation remains healthy and fully operational, officials said.

A couple months ago, the Air Force delayed this mission to review changes made to the rocket's safety destruct system.