Air Force launches new GPS satellite

Upgraded orbiter to deliver greater accuracy

The seventh of eight enhanced second-generation global positioning satellites (GPS) blasted into space early on March 24 from Cape Canaveral Air Force Station, Fla. The two-ton GPS satellite, designated GPS IIR-20(M), flew on a three-stage Delta II rocket and reached orbit after a 68-minute flight.

This satellite is the penultimate of an eight-block program to replenish GPS satellites for the military as well as for civilian use. Since it launched the first GPS satellite in 1978, the Air Force has periodically upgraded the constellation with new capabilities.

The features built into this latest program block include two new military signals for improving accuracy, increased signal power to receivers on the ground, enhanced encryption, anti-jamming capabilities and a second civil signal to provide dual frequency capability with better resistance to interference. In addition, this orbiter carried a research and development demonstration payload for transmitting a third civil signal known as L5.

“Every year we have made the GPS signal better, every year the accuracy of the system has improved," said Gen. Robert Kehler, the Air Force Space Command commander. "And that is what is going to continue to happen."

Designed to operate for 10 years, GPS satellites orbit the Earth every 12 hours and provide a key capability for military situational awareness platforms such as Blue Force Tracking. A third generation of GPS satellites is set to begin operations in 2013.

The March 24 launch had been slated for June 2008, but problems with the Delta II rocket kept the orbiter grounded for almost a year. Delta II rockets are near the end of their life cycle, having first blasted off 20 years ago. They were designed in the wake of the 1986 Space Shuttle Challenger disaster, when the Air Force needed alternate means to lift hardware into space. The last Delta II ever to hold an Air Force payload is set to carry the eighth enhanced second generation replenishment GPS satellite in August.

Although it was launched from an Air Force facility, the rocket belonged to a private-sector rocket launch services consortium named the United Launch Alliance, a joint venture formed in 2006 between Boeing and Lockheed Martin. The two companies previously competed to launch government payloads, but consolidated when it became clear that a commercially-viable rocket launch market might not exist.

The United Launch Alliance had tried only days earlier, on March 18, to launch the Air Force’s second Wideband Global Satcom into space using an Atlas V rocket at Cape Canaveral, but scrubbed it following the discovery of an upper-stage liquid oxygen leak.

About the Author

David Perera is a special contributor to Defense Systems.

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