File image of GPS 2R satellite mounted atop the Delta 2 rocket third stage and spin system in the Cape processing building. Photo: Lockheed Martin

A Boeing Delta 2 rocket was damaged in a freak accident last week as workers attached a Global Positioning System satellite to the booster at Cape Canaveral's launch pad 17B, the Air Force acknowledged Tuesday.

The $50 million replacement satellite for the U.S. military's GPS navigation network had been scheduled for liftoff November 7. But repairs are expected to delay the mission at least a month and could also push back the January launch of NASA's fourth Great Observatory.

Air Force and Boeing officials have begun a fact-finding investigation to determine what happened in Friday's mishap.

Initial reports indicate the pad's lifting crane tried to pull upward the canister containing the satellite after the structure had been bolted to the rocket, possibly due to miscommunication between workers.

The Lockheed Martin-built GPS 2R-8 satellite was tested and prepared for launch inside a government building at the Cape. Before traveling to the launch pad, workers mounted the craft atop a solid-fueled motor that serves as the Delta 2's third stage.

The satellite and motor were then enclosed in a protective canister and transported to pad 17B. The duo was hoisted into the service tower and lowered into position for mating with the vehicle's second stage.

"During the pre-launch mating process, the canister holding the combined stack of the GPS 2R-8 spacecraft and third stage was inadvertently lifted from the second stage of the Delta 2 after it had been secured," said Air Force spokesman Joe Davidson. The Air Force oversees GPS launches.

"No one was injured. However, some flight hardware was damaged. Full extend of the damage will be determined by inspection following return of the GPS and the Delta 2 third stage to the processing facility."

Early reports suggest the damage is "mainly" on the rocket.

Illustration of a Delta 2 rocket similar to the version used to launch GPS satellites. Photo: Boeing

It's the second time in three years a GPS satellite has been involved in an incident at the launch pad. In May 1999, the third GPS 2R craft got wet when the pad's clean room leaked during a severe storm. The craft was disassembled for inspections and awaits future use.

The launch of GPS 2R-8 has been delayed since the spring due to Air Force-ordered reviews of changes made to the rocket's safety destruct system and wiring concerns.

The military hasn't launched a fresh GPS satellite since January 2001 because the constellation has been healthy.

The GPS network features 24 satellites working in concert to provide precision location, speed and timing information to guide U.S. military troops, aircraft, submarines, ships and weapons around the globe. The two dozen satellites are split into six groups, or orbital planes, with four primary spacecraft in each.

NASA satellite faces possible delay, too
The delayed GPS launch from pad 17B could cause a ripple effect, postponing the next Delta flight from that seaside pad.

Complex 17 has two pads -- A and B. Both can be used for launches of Delta 2 rockets that are propelled by 40-inch diameter strap-on solid-fueled boosters, such as GPS missions. But only pad B has been modified to handle the larger, 46-inch solid rocket boosters used by the Delta 2-Heavy and Delta 3 launchers.

File image of Delta 2 rockets sitting atop pads 17B (left) and 17A (right) at Cape Canaveral. Photo: U.S. Air Force

NASA's Space Infrared Telescope Facility, or SIRTF, is scheduled for liftoff January 9 aboard the first Delta 2-Heavy rocket for a $720 million mission to observe planets, stars, galaxies and other celestial objects in the Universe.

Space agency sources said Tuesday that SIRTF's liftoff could be delayed three to four weeks -- the amount of time needed to repair the GPS rocket, launch it, refurbish the pad and then assemble SIRTF's Delta 2.

One possibility -- still in the early stages of discussion -- would see the GPS rocket destacked and moved to the vacant pad 17A for launch. Pad 17A can't accommodate the solid boosters for SIRTF but can support GPS. Such an option, if approved, could allow the SIRTF rocket to be stacked in December to permit an on-time launch January 9.

NASA wants to launch SIRTF during a two-month window that extends to March 9.

SIRTF is the fourth and final member of NASA's Great Observatories series to study the Universe in a different kind of light -- visible, gamma rays, X-rays and infrared. The three earlier spacecraft are the Hubble Space Telescope, Compton Gamma Ray Observatory and Chandra X-ray Observatory.