Pushing forward with plans to launch the Air Force's fifth Wideband Global SATCOM communications satellite on May 22 to give the expanding constellation worldwide coverage, the craft departed its cleanroom Monday night and headed for the Delta 4 rocket's launch pad.

File image of Delta payload leaving Astrotech. Credit: NASA

United Launch Alliance workers at Cape Canaveral's Complex 37 hoisted the spacecraft atop the booster on Tuesday to complete assembly of the 217-foot-tall rocket.

The Wideband Global SATCOM 5 spacecraft, built by The Boeing Company under a $342 million contract, will relay high-data-rate, large-volume communications such as voice, video conferencing, intelligence files and weather data.

WGS 5 is headed for geosynchronous orbit 22,300 miles up to join the Pentagon's communications infrastructure that routes information between civilian leadership and military forces around the globe.

"The (WGS) system provides high-capacity communications to the Department of Defense, the White House Communications Agency, the Department of State and an increasing number of international partners," said Gen. William Shelton, leader of Air Force Space Command.

"Once WGS 5 becomes operational, the constellation will be postured to provide worldwide coverage."

This satellite will aim its coverage zone over the Americas, providing X- and Ka-band communications to U.S. Northern Command, Southern Command and other continental United States-based users, officials said.

The mission patch symbolizes WGS 5 becoming the second Block 2 satellite in orbit, joining the three Block 1 spacecraft.

WGS 1 was launched in October 2007 to cover the vast U.S. Pacific Command that stretches from the U.S. western coast all the way to Southeast Asia.

WGS 2 satellite followed with an April 2009 launch to serve U.S. Central Command and the forces in Afghanistan, Iraq and other parts of Southwest Asia.

WGS 3 went up in December 2009 to cover U.S. European Command and U.S. Africa Command, plus lend additional support over the Middle East.

WGS 4 inaugurated the upgraded Block 2 series for improved communications with unmanned aerial drones when it was launched in January 2012 to cover the Middle East and Southeast Asia for use by U.S. Central Command and U.S. Pacific Command.

Boeing is building a fleet of 10 WGS satellites, and the next satellite launching later this summer, WGS 6, was financed in cooperation with Australia.

"This is dedicated military satellite communications. It's now international in nature. We've got international partners signed up with this. In fact the Australians have purchased a satellite to buy into the system," Shelton said.

This illustration depicts the major elements of the Delta 4 rocket and WGS 5. Credit: ULA

The WGS 5 satellite was shipped from Boeing's factory in Los Angeles to the Kennedy Space Center runway, then taken to the commercial Astrotech spacecraft preparation facility in neighboring Titusville on March 9. It has undergone final testing, the loading of maneuvering fuel and encapsulation within the rocket's nose cone since then.

Monday night's 25-mile trip from Titusville entered KSC to drive by the Vehicle Assembly Building and shuttle launch pad before heading down the beach at the Cape Canaveral Air Force Station to Complex 37 where the Delta 4 awaits.

The payload was raised into the gantry Tuesday for mating to the rocket to begin the final two weeks of pre-flight work.

The move began the same day as the GPS 2F-4 navigation satellite was transported from its military cleanroom to the Atlas 5 rocket facilities at Complex 41 for mating to that booster. The mission is scheduled for liftoff May 15, kicking off two United Launch Alliance flights for the Air Force in just 7 days.

The May 15 launch of Atlas with GPS will be possible during a window extending from 5:38 to 5:56 p.m. EDT.

The May 22 launch of Delta with WGS will be possible during a window extending from 8:26 to 8:58 p.m. EDT.