The final member of the U.S. military's most secure satellite communications constellation ascended into the sky Tuesday where it will relay highly sensitive information between the president and the armed forces.

The Titan 4B rocket launches Tuesday with Milstar 6. Photo: Russ Underwood, Lockheed Martin Space Systems

The $461 million Lockheed Martin Titan 4B rocket ignited at 9:43 a.m. EDT, sending a torrent of fire and smoke blasting from the exhaust duct at Cape Canaveral Air Force Station's Complex 40.

More than six-and-a-half hours later, the Military Strategic and Tactical Relay spacecraft was successfully deployed into geostationary orbit about 22,300 miles above Earth.

The $800 million Milstar 6 satellite will undergo weeks of tests before the Air Force declares it fully operational in May for a 10-year life. The Lockheed Martin-made bird joins five other Milstars in space, although one suffered a launch malfunction in 1999 and ended up in a graveyard orbit.

Controllers will position the satellite in view of the U.S. for the checkout. Its ultimate operational location has not been announced and is "under the cognizance of U.S. Strategic Command," Milstar program officials told Spaceflight Now.

Developed in the 1980s, the Milstar satellites began launching in 1994 to form a communications network for senior U.S. officials that would be dependable, jam-proof and immune from interception.

Today, Milstars are linked together in a space-based ring that covers virtually the entire planet to beam voice, data and imagery transmissions. The "cross-linked" satellite system eliminates the need for land-based relay stations, reducing the chances of communications being intercepted on the ground, the Air Force says.

"Milstar is literally the FedEx of telecommunications. If you have to get a message through, Milstar is your choice," said Christine Anderson of the Air Force's MILSATCOM joint program office.

"There are over a thousand Milstar terminals on ships, aircraft and ground vehicles, many of these are operating in Iraqi Freedom today," Anderson added.

An artist's concept of a Milstar satellite in space. Credit: Lockheed Martin

The Milstar constellation played a key role in the command and control of forces involved in the recent rescue of former POW Private First Class Jessica Lynch.

"This satellite system is a critical communication asset for each branch of the military." Air Force Launch Director Lt. Col. Tony Cotton said.

"It allows our highest level military leaders to communicate with battlefield commanders. Our secure communication capabilities on and off the battlefield are greatly improved with the use of this satellite constellation. I am proud to be part of the team that put the final critical satellite of this outstanding constellation into space."

This new satellite is the fourth built with the Medium Data Rate payload. Manufactured by Boeing Satellite Systems, the MDR has 32 channels, which can process data at speeds of 1.5 megabits per second.

The spacecraft also features the Low Data Rate payload, built by Northrop Grumman. LDR can transmit 75 to 2400 bps of voice and data over 192 channels in the Extremely High Frequency range.

The first two Milstar satellites launched in 1994 and 1995 only carried LDR. Milstar 3 through 6 feature both LDR and MDR. The later satellites sport a 600 percent increase in communications capacity over the first two Milstar satellites, the Air Force said.

The Milstar spacecraft are the U.S. military's most technologically advanced telecommunications satellites. Photo: Russ Underwood, Lockheed Martin Space Systems

Milstar can now send an air tasking order to its destination in less than six seconds, a vast improvement from years past when it would take an hour. Officials also said an 8x10 image used to take 22 hours to send will be transferred in just two minutes.

With the completion of Tuesday's launch, the 35th for a Titan 4 rocket since 1989, just four more missions remain on the schedule.

"Being part of the historical fly out of this nation's heavy-lift workhorse provides added significance for all of us on the launch team, especially due to the fact that the payloads boosted on the Titan 4s are so critical to national security," Cotton said.

Crews will be preparing the Complex 40 pad for the September 15 launch of a classified National Reconnaissance Office cargo. Originally slated to fly last June, troubles with the payload prompted the Air Force to delay the launch until after Milstar 6. In fact, Tuesday's mission used the Titan 4 core stages and solid rocket boosters initially prepared for the NRO.

The deployment of another Defense Satellite Program missile warning satellite is scheduled for January 17. That launch will feature a Titan 4 rocket and a Boeing-made Inertial Upper Stage booster.

The Titan 4 era at Cape Canaveral will draw to a close in October 2004 with another secret NRO launch. Designated B-30, that mission was supposed to fly from Vandenberg Air Force Base in California. But the NRO shifted the launch to the Cape for undisclosed reasons.

The final voyage of Titan 4 is currently scheduled for February 2005 from Vandenberg carrying yet another NRO cargo.

Video coverage for subscribers only:
   VIDEO: TITAN 4 ROCKET LAUNCHES WITH MILSTAR 6 QT
   VIDEO: LAUNCH SCENES FROM PRESS SITE ON CAUSEWAY QT
   VIDEO: RETROSPECTIVE VIDEO ON HISTORY OF TITAN QT
   VIDEO: PRE-LAUNCH NEWS CONFERENCE HELD SATURDAY QT
   VIDEO: FOOTAGE OF MILSTAR ASSEMBLY IN FACTORY QT
   VIDEO: MILSTAR SPACECRAFT SHIPPED TO THE CAPE QT
   VIDEO: SATELLITE ENCAPSULATED BY NOSE CONE QT
   VIDEO: ANIMATION OF MILSTAR ASCENT TO ORBIT QT
   PANORAMA: 360-DEGREE VIEW OF TITAN 4 ON THE PAD QT VR
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