Rocket-launch manifests rarely play out as envisioned at the beginning of a given year, but 2005 is proving unusually disruptive for Boeing Co., which is unlikely to get more than six of some 13 previously scheduled Delta missions off the ground before January.

A number of circumstances have conspired to depress Boeing’s launch activity, including a grounding of the entire Delta fleet due to a battery problem, satellite delays and conflicts at the U.S. Air Force launch ranges. Company engineers also got wrapped up in reviews of a mishap involving the Delta 4 heavy-lift rocket in a December test launch.

The good news is that the Delta 4 has been cleared to resume flying, and is now slated to launch a U.S. government weather satellite July 28 or 29. The Geostationary-orbiting Operational Environmental Satellite-N (GOES-N) had been scheduled for May, but slipped due to a number of concerns with the Delta 4.

That mission was rescheduled for June, but delayed again when the battery problem cropped up during pre-launch testing. That issue prompted the Air Force to ground both the Delta 4 and the Delta 2 rockets, which comprise the entire Boeing fleet.

The batteries in question power a system on the second stage that destroys the rocket if safety issues arise during flight. Vibration testing on the GOES-N satellite’s Delta 4 launcher ruptured wires that connect the batteries’ cell plates to the terminal, according to Robert Villanueva, a spokesman for Boeing Expendable Launch Systems of Huntington Beach, Calif.

Gary Davis, director of systems development at the National Oceanic and Atmospheric Administration’s satellite and information services division, which operates U.S. civilian weather satellites, said the batteries have been rebuilt and requalified for use with the Delta 4 rocket for GOES-N.

But the Delta 2 rockets still need to undergo a series of tests with the rebuilt batteries that are expected to run through mid-August, Villanueva said. The Delta 2 experiences a higher level of vibration during launch, necessitating the additional tests, he said.

The continued grounding of the Delta 2 has held up the launches of new GPS navigation spacecraft, according to a source close to that program. Three Lockheed Martin-built GPS satellites were expected to launch aboard Delta 2 rockets in 2005, but the delay associated with the battery issue has moved the first of those missions into September, the source said.

The Air Force generally staggers navigation satellite launches by several months, so the second has been moved into December, with the third expected in 2006, the source said.

The battery problems also have delayed a NASA cloud observation satellite that was slated to launch July 22 aboard a Delta 2 from Vandenberg Air Force Base, Calif., according to a NASA expendable rocket status report released July 22. NASA now expects to launch the Cloudsat/Calipso satellite Sept. 29.

Previous plans for 2005 also called for Delta rockets to launch four spy satellites for the National Reconnaissance Office. But due to issues with the spacecraft and the rockets, only one of those missions, known as National Reconnaissance Office L22, still is expected to fly in 2005, according to a Pentagon official. That satellite, which had been slated to launch in March, now is not expected to get off the ground before mid September, and could slip again, the official said.

The Delta 4 delays also include the first operational launch of the heavy-lift variant, which was scheduled to launch an Air Force missile warning satellite in September. The December demonstration of the Delta 4 Heavy failed to put its payloads into orbit. The launch of the Defense Support Program missile warning satellite now is not expected to take place before late January, according to industry officials. The battery problem was a factor in that delay, an industry source said.

Launch range conflicts, meanwhile, led the Air Force to scrap plans to launch the first Wideband Gapfiller communications satellite aboard a Delta 4 rocket in December. That mission now is slated for late 2006, according to Air Force officials. The Air Force has moved a Wideband Gapfiller launch aboard a Lockheed Martin Atlas 5 rocket ahead in the manifest, to early 2006.

Delays with a National Reconnaissance Office spacecraft slated to ride on the last Titan 4 also have affected Boeing’s launch plans. That mission, from Vandenberg, has been delayed from this summer to October. This has delayed other Vandenberg missions, including the Delta 2 launch of an Air Force weather satellite that was suppose to take place in June. That mission now is not expected to take place before November.

Two Delta 2 missions have been conducted this year, the January launch of NASA’s Deep Impact probe and the May launch of a polar-orbiting civilian weather satellite.