"The last piece of the Atlas 5 launch system left to test was the integration of vehicle and launch pad, which has now been verified to perform as designed and advertised," said John Karas, vice president of Atlas Development.

"We loaded liquid oxygen and RP-1 on the Atlas booster and liquid oxygen and liquid hydrogen on the Centaur upper stage using the new ground systems of our Atlas 5 launch complex, all controlled from the new Atlas 5 Spaceflight Operations Center. This accomplishment is a great leap forward in being ready for the Atlas 5 inaugural launch."

The process of checking out the vehicle as if for launch, including tanking and detanking propellants, is called a "wet dress rehearsal," or WDR. WDR is the major pre-launch test that proves all airborne and ground hardware and software are ready to perform.

During WDR the launch team simulates the countdown, which in the case of Atlas 5 will improve upon the Atlas II and III procedures. Atlas II and III are currently performing at 100 per cent Mission Success, with 60 consecutive successful launches over nine years. A total of three WDRs will be performed before the first Atlas 5 launch.

As a prelude to WDR #1, the vehicle rolled to the pad for the first time on its mobile launch platform (MLP) from the vertical integration facility (VIF) Wednesday, March 6. In that first on-pad operation, the team checked numerous subsystems and the kerosene-like fuel known as RP-1 was loaded on board the Atlas and then unloaded before rollback to the VIF.

The Atlas 5 made the 1,800-foot journey to the pad in 30 minutes. In the first demonstration of the robust, all-weather qualities of the launch vehicle, AV-001 stood outside for 31 hours straight. As it stands exposed on the launch pad, Atlas 5 is able to withstand winds of 60+ mph.

WDR #1 was performed over a five -day period that began Monday, March 11. Centaur upper stage cryogenic propellants - super-cold liquid oxygen and hydrogen - were loaded and unloaded on Wednesday, March 13. Liquid oxygen was loaded on board the Atlas on Thursday, March 14.

The entire process concluded on Friday, March 15, with rollback to the VIF. During the five days, the rocket spent 90+ hours on the launch pad through a variety of Central Florida weather conditions including wind, rain and lightning, further demonstrating the robust design of the system.

WDR was deliberately expanded from normal operations to allow for extra development testing. Normal launch day operations will take only 11 hours from the time the vehicle is moved from the VIF to launch.

"Once again the entire Atlas 5 team has done a fabulous job achieving another critical program milestone," said Col. Bob Saxer, the Air Force EELV System Program Director, who was on console with Col. Sue Mashiko during the initial rollout and tanking.

"The technical challenges associated with bringing a brand new launch vehicle and launch pad to life are not insignificant. John Karas and the entire Atlas 5 technical team are to be commended for the outstanding job they've done; successfully tanking the entire vehicle, taking it to flight pressures, and counting down to T-minus 4 minutes during the first WDR is very impressive. I look forward with great anticipation to our first launch."

The Atlas 5 launch system improves on performance as well as reliability. Today's Atlas II and III families lift up to 9,900 pounds to geosynchronous transfer orbit (GTO) and have one payload fairing size. The Atlas 5 Common Core Booster can fly missions ranging from 11,000 pounds up to 19,000 pounds to GTO with either a four-meter or five-meter payload fairing without booster or upper stage changes.

Configuring the vehicle can be done at the launch site rather than in the factory. The Atlas 5 also improves mission reliability by reducing active booster single-point failure components from hundreds to a handful because most systems are simplified, made redundant or eliminated altogether.

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