Inching along at barely a walking pace, Boeing's first Delta 4-Heavy rocket was carefully driven from an assembly hangar to its Cape Canaveral launch pad Tuesday afternoon where it will undergo seven months of tests before blasting off on a qualification flight.

Boeing's maiden Delta 4-Heavy rocket makes its way to pad 37B on Tuesday. Photo: Justin Ray/Spaceflight Now SEE ROLLOUT PHOTO GALLERY

The 170-foot long vehicle emerged from the Horizontal Integration Facility at 3:15 p.m. for the trip to pad 37B. With workers and news media representatives following along and snapping photos, the Delta 4-Heavy reached the pad more than an hour later.

Technicians were to spend Tuesday evening and early Wednesday preparing the rocket to be raised vertically. The cradle-like pallets upon which the rocket is resting will be tied down to the Fixed Pad Erector on the pad's surface. The diesel-powered transporter used to drive the rocket to the pad then will disengage from the pallets and pull away.

On Wednesday, the erector system, with its two hydraulic pistons, will lift the rocket upright, putting the vehicle on the pad's launch table. After the rocket is set, technicians will unhook the booster from the pallets.

The erector, along with the pallets, is lowered back to the ground. The transporter then returns to the erector to retrieve the pallets for reuse on another mission.

The Delta 4-Heavy rocket will remain on the pad through its launch, now targeted for the afternoon of July 3.

Boeing's maiden Delta 4-Heavy rocket makes its way to pad 37B on Tuesday. Photo: Justin Ray/Spaceflight Now SEE ROLLOUT PHOTO GALLERY

Starting early next year, a series of tests will be conducted in which the rocket is loaded with super-cold liquid oxygen and liquid hydrogen. The events are designed to gather information about how the massive rocket behaves under the dynamic thermal conditions and give engineers experience fueling the stages. Two dress rehearsals to practice what launch day will be like follow in May and June.

The launcher consists of three Common Booster Cores, each with a hydrogen-fueled RS-68 main engine, and a cryogenic upper stage. The stages were assembled together in the Horizontal Integration Facility over the past several months.

Next June, the dummy payload and the rocket's nose cone will be installed at the pad, increasing the vehicle's overall height to 235 feet.

The U.S. Air Force paid for this maiden flight of Delta 4-Heavy to carry only an instrumented satellite simulator. The test launch will prove the rocket operates properly before critical national security payloads are flown atop the vehicle in the future.

NASA, too, is looking at the rocket as a potential launcher of the Orbital Space Plane.

An overhead view of the three Common Booster Cores of the Delta 4-Heavy rocket as seen in the Horizontal Integration Facility earlier this year. Photo: Boeing

For more on the Delta 4-Heavy, see our feature story published last month.