For the first time a rocket is sitting atop Boeing's launch pad for the new millennium at Cape Canaveral as activities continue for the maiden flight of Delta 4 next spring.

The Common Booster Core rolls up the road to the launch pad. Photo: Carleton Bailie

Last Wednesday workers rolled a Common Booster Core -- the first stage of the next-generation Delta 4 rocket -- from the Horizontal Integration Facility to the pad at Complex 37 on a specially-designed motorized transporter. The half-mile trip took less than an hour, said Mike Woolley of Boeing's Launch Site Security and External Relations.

The rocket stage spent the night sitting on its side before being erected to stand tall at the former Apollo-era pad that has been rebuilt from the ground up over the past couple of years.

This Common Booster Core, with an RS-68 main engine mounted to its bottom, is serving as Boeing's test unit for the Delta 4 fleet. It underwent four firings earlier this year at NASA's Stennis Space Center in Southern Mississippi to simulate launches for the combined stage and engine.

The 154-foot tall, 54,000-pound rocket stage then came to Cape Canaveral in May aboard the Delta Mariner cargo vessel for a series of exercises and mechanical tests in the Horizontal Integration Facility -- the new 75,000-square-foot building where stages of the Delta 4 rocket will be mated together.

The rocket begins to be erected vertically at Complex 37. Photo: Carleton Bailie

Over the past three months, the rocket was attached to the Launch Mate Unit and Elevating Platform Transporter. The laser alignment system, originally developed by Boeing's commercial aircraft division, was also checked out in the HIF for use in the future to give technicians precision accuracy when rockets are assembled for flight.

"The pathfinder through the HIF has gone very smoothly. There are always issues that crop up and you have to tackle them, but that's why you perform the pathfinder," Woolley said in an interview Friday. "No major items jumped up and grabbed us."

After being moved to the pad, the Fixed Pad Erector rotated the stage vertical and set it on the launch table in a process than took about 45 minutes to complete. Once over the table, the vertical positioning latches locked down and the load was transferred to the launch table, Woolley explained.

The erector was then lowered back to the ground and the transporter returned to the HIF building.

The goal of the pad pathfinder activities, which will continue for the next month, is to ensure everything fits together in the mechanical sense.

"We are going to rotate the swing platforms into closed position, verify all the clearances, ensure we have the correct access to the vehicle, do the appropriate mechanical tests and make sure everything is fine and copacetic."

The stage is rotated upright to sit atop the pad's launch table. Photo: Carleton Bailie

In addition, an inert strap-on solid rocket motor will be taken to the pad, hoisted from the ground and attached to the stage. This test is another critical demonstration in advance of the first Delta 4 launch since that flight will feature a rocket with two solid motors.

Once the pad checks are finished, the stage will be lowered back to the ground and rolled off the pad in reverse of how it got there. The so-called "de-erection" is actually part of the pathfinder exercises, Woolley said.

"Our philosophy is if the booster or satellite have a problem that's going to have to remain on the pad awhile, we'll just demate the satellite and de-erect the booster and take it back to Horizontal Integration Facility."

Unlike today's Delta 2 and 3 rockets that are assembled on the launch pad in the weeks leading up to liftoff, the Delta 4 will stay on its pad for a matter of days before liftoff. And with the concept of horizontal processing, one Delta 4 can be rolled off the pad to make way for another if a problem arises all in hopes of keeping the launch schedule from backing up.

The fixed umbilical tower is the structure to the left and the mobile service tower is the massive structure to the right. Photo: Carleton Bailie

The stage being used for the pathfinders is only a test unit and not a flight-worthy vehicle. The rocket that will fly the inaugural Delta 4 mission is currently in the final stages of qualification checks at Boeing's manufacturing plant in Decatur, Alabama, Woolley said. It is slated for transport to the Cape in September by the Delta Mariner ship.

Part of the rocket's activities once delivered to Florida will be picking up where the test article left off -- performing the electrical and propellant checks at the launch site.

The vehicle will be taken to the pad for such tests, and will even undergo a flight readiness firing early next year with the RS-68 engine roaring to life for a few seconds on the pad.

"One of Boeing's concepts is to reduce the risk to the first flight, to the satellite, so we run it through a lot of pathfinding events to ensure the systems work well."

There's still a considerable amount of work before the first Delta 4 rocket blasts off, but Woolley says getting the test vehicle out to the launch pad has increased the level of excitement "tremendously" at Boeing.

"This is a very good milestone for us...We are extremely happy about this."