New communications craft launched for U.S. military
BY JUSTIN RAY
Posted: December 5, 2009
The Delta 4 rocket debuted its latest variant with a display of power and precision Saturday night, successfully using an energetic creation to heave a vital communications satellite into space for the U.S. military.
Four solid-fueled boosters affixed to the rocket in pairs provided the impressive kick that propelled the 217-foot-tall Delta into the nighttime sky, augmenting the thrust from the first stage's hydrogen-fed main engine.
The hotrod rocket is known as the Medium+ (5,4) configuration. It's distinguished by a five-meter composite payload shroud, a similarly-sized upper stage and the quad arrangement of solid rockets. Previous Medium+ rockets have flown with the smaller four-meter nose cone, an upper stage that carries less fuel and only two solid motors.
The United Launch Alliance Delta 4 family was conceived around a modular design, allowing mission planners to match different rocket configurations with the payloads they carry. Earlier flights spanned the spectrum of options ranging from the simplest version featuring just two stages all the way to the triple-body heavy-lifter that can haul the largest satellites.
The spacecraft needing a ride to space Saturday night was the Air Force's third Wideband Global SATCOM communications satellite, weighing a hefty 12,800 pounds. The "5,4" variant of Delta 4 fit the role of launching the craft into the desired supersynchronous transfer orbit.
The cryogenic main engine and all four solids were ignited on the launch pad, causing the rocket to depart the Florida spaceport in a hurry.
The strap-on motors fired for 94 seconds and then separated. The RS-68 engine continued burning through the initial four minutes of flight by consuming liquid hydrogen and liquid oxygen.
Shortly before the first stage's burn concluded, having already left the atmosphere, the 47-foot-long nose shroud covering the satellite was jettisoned.
The first stage finished its job and separated about 100 nautical miles over the ocean, leaving rocket's upper stage and cryogenic RL10B-2 powerplant to perform a lengthy firing to achieve an intermediate parking orbit and then a second, brief burn near the western coast of Africa that sent the payload toward an orbit that was targeted to hit 237 nautical miles at perigee, 36,167 nautical miles at apogee and inclined 24 degrees.
The payload separated from the launcher just before T+plus 41 minutes while soaring away from the planet over the Indian Ocean.
"Now more than ever, our nation depends on our ability to successfully deliver space-based capabilities with 100 percent mission success," Col. Gary Henry, commander of the Air Force's Launch and Range Systems Wing.
Known as WGS 3, this satellite is the third in a major program to upgrade to the military's main communications infrastructure, replacing the aging Defense Satellite Communications System (DSCS) spacecraft. Each WGS has 10 times the capacity of a DSCS satellite, allowing users to process and receive data quicker than ever before.
"WGS is the nation's next generation wideband satellite communications system that will increase the security, availability and bandwidth of communications for our globally-engaged service men and woman," said Lt. Col. Dave Hook, commander of the 5th Space Launch Squadron at Cape Canaveral.
The satellites supply communications such as maps and data to soldiers on the battlefield, relay video from unmanned aerial reconnaissance drones, route voice calls and data messaging, and even offer quality-of-life considerations like television broadcasts and email delivery to the troops.
WGS 1 entered service last year to cover the vast Pacific Command that stretches from the U.S. western coast all the way to Southeast Asia. The WGS 2 satellite launched earlier this year was placed into operation over the Indian Ocean for use by U.S. Central Command to provide coverage for the warfighters in Afghanistan, Iraq and other parts of Southwest Asia.
The new WGS 3 satellite will be positioned above the Eastern Atlantic at an orbital slot of 12 degrees West longitude. Its broad reach will cover U.S. European Command and U.S. Africa Command, plus lend additional support over the Middle East.
"WGS 3 is the next step in deploying Wideband Global SATCOM to augment and eventually replace the legacy Defense Satellite Communications System, or DSCS, which has been the Department of Defense's backbone for satellite communications over the last three decades," said Col. Bill Harding, vice commander, Military Satellite Communications Systems Wing.
"WGS 3 is slated for operations over EUCOM and AFRICOM and will provide an order of magnitude increase in military communications bandwidth for Soldiers, Sailors, Airmen and Marines."
The satellite will be maneuvered into a circular geostationary orbit 22,300 miles above the planet where it can match the Earth's rotation and appear parked over one area of the globe. On-orbit testing is scheduled to last a few months, enabling the craft to begin full use next April.
The WGS spacecraft are constructed around Boeing's powerhouse 702-model design used by commercial satellite operators. But within the WGS craft are Ka- and X-band military communications packages.
The WGS craft offer X-band communications, like the venerable DSCS satellites, to connect with military users anywhere within the field of view from orbit.
What's new on WGS is Ka-band communications. Officials describe the extra frequency as a way of serving up large amounts of information for reception by U.S. and allied forces across a wide area using the so-called Global Broadcast System, or GBS.
"The GBS is like DirecTV to the warfighter. With the emerging requirements for more and more Predator and Reaper unmanned aerial system data, the GBS is allowing us to double the amount of full motion video we are able to carry," Harding said. "With the GBS data, it allows us to bring that full motion video down to small, one-meter terminals."
The satellites also adjust and shift their multiple beams of coverage, a feature that is employed as local hotspots on Earth move.
"That is a key advance for our warfighters of giving them the communications where they need it, when they need it," said Mark Spiwak, the WGS program director for satellite-builder Boeing.
"We can make (the beams) more oblong, we can put notches in them, we can make them bigger and global. But we can shape the beams and shape the throughput."
The Air Force says nine DSCS satellites remain in use while the new WGS craft are continuing to be built and deployed.
"We're trying to squeeze as much as capability out of the DSCS birds as we possible can. We continue to monitor the capability of the spacecraft and how much fuel in there," Harding said.
With the first two WGS satellites already in use and the third en route, the Air Force seems pleased with the new constellation of spacecraft they are assembling.
"We're getting great feedback in terms of the support they are providing," Harding said. "The first one went up over (Pacific Command). As you realize, that particular theater deals with the tyranny of distance a lot more than some of the other theaters, so (satellite communications) is extremely important to them. Of course, the X-band -- the DSCS replacement capability -- plus the Ka-band provide them not only a lot of bandwidth...but a lot more coverage area. So there's a lot of antennas and we're able to cover forces no matter where they are in the Pacific."
"Quality-of-life for the folks on the ships has been significantly increased due to WGS being fielded," Spiwak added, noting that WGS 1 can provide 24/7 Internet and television to the military deployed across the Pacific.
Three more WGS satellites are under construction at Boeing's manufacturing plant in El Segundo, California. They are incorporating a slight upgrade from the previous trio of spacecraft and should be ready to begin launching in 2011.
"We are very active on satellites 4, 5 and 6. In fact, before the end of the year we will be assembling the F4 satellite into a complete satellite," Spiwak said.
"Those satellites are on schedule...we've got the formula now."
Harding said the WGS program -- and its six satellites ordered thus far -- is valued at $2.1 billion.
"WGS addresses our military's ever-growing appetite for high-bandwidth satellite communications," said Craig Cooning, vice president and general manager at Boeing Space and Intelligence Systems. "We're now working with the Air Force to determine how future WGS satellites could be enhanced to handle missions involving airborne intelligence, surveillance and reconnaissance, and communications-on-the-move."
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