The July 15 launch from Cape Canaveral’s Launch Complex 41 of the Air Force/Boeing GPS 2F-10 navigation spacecraft on a United Launch Alliance Atlas V 401 marks the 20th anniversary of a fully operational GPS constellation.
As the new GPS is checked out in space, a second military space mission is also being prepared on Launch Complex 37B. That mission is the seventh USAF Wideband Global SATCOM (WGS) satellite planned for liftoff July 22 on a Delta IV Medium Plus with four solid rocket boosters. The July 22 Delta IV liftoff is within a 45-minute launch window that opens at 8:07 p.m. EDT and closes at 8:52 p.m. EDT.
The new GPS will replace the 11-year-old GPS 2R-11 launched in 2004. That satellite will take on a backup role in the expanded 31 satellite GPS constellation that ensures at least 24 satellites are operational at any given time, with mostly four spacecraft in view of any given spot on Earth. As part of this change, the 19-year-old GPS 2A-26, launched in 1996, will be decommissioned.
Powered by 860,000 lbs (390,089 kg) of thrust from its Russian Energomash RD-180 engine, the Atlas flew northeast from the Cape on an azimuth of 45.8 degrees. The first stage separation and initial ignition of its Centaur 22,900-lb (10, 387-kg) thrust second stage came at about 4 minutes, 19 seconds in the flight. That burn lasted about 18 minutes over the North Atlantic.
Then, after coasting for 3 hours, 17 minutes, the Centaur was restarted for a roughly 90-second second burn, followed by satellite release south of Australia 3 hours, 23 minutes after launch.
The Atlas placed the 3,400-lb (1,542-kg) GPS into a 12,541-mile (20,182-km) orbit, inclined 55 degrees.
The GPS system became operational in 1995 when the last spacecraft to complete an initial constellation of 27 spacecraft was launched into space. This included 24 primary and three backup satellites. Since the Navstar 1 first GPS test satellite’s launch in 1974, 70 GPS spacecraft have been launched.
The flight also marked the 55th launch of an Atlas V since the RP-/oxygen powered rocket began flying with an oxygen/hydrogen single engine Centaur from both the Cape and Vandenberg AFB, Calif.
The GPS system is operated and controlled by the 50th Space Wing, located at Schriever Air Force Base, Colo.
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