By Irene Klotz
CAPE CANAVERAL, Florida (Reuters) - An unmanned Atlas rocket blasted off from Cape Canaveral Air Force Station on Wednesday to deliver an upgraded global positioning system satellite into orbit.
The 189-foot (58-meter) tall rocket, built and launched by United Launch Alliance, a partnership of Boeing and Lockheed Martin, soared into blue skies over Florida's east coast at 5:38 p.m. EDT.
Perched on top of the rocket was a 3,400-pound (1,542 kg) Boeing-built GPS 2F satellite, the fourth of 12 upgraded spacecraft expected to be added to the orbiting constellation over the next several years.
"It's a big moment for all of us," Travis Pond, a lieutenant with the U.S. Air Force 45th Space Wing at Cape Canaveral Air Force Station, said during a United Launch Alliance launch webcast.
The navigation satellites are used by the U.S. military and allies, as well as millions of civilians. The upgraded versions offer greater accuracy, enhanced internal atomic clocks, better protection against signal jamming and a new signal for commercial aviation.
The satellite, which cost about $121 million, will replace a spacecraft launched in 1996 that already is twice past its design lifetime. That satellite will be repositioned for use as a spare.
With Wednesday's launch, the GPS network will include 31 operational satellites in orbit.
The next GPS launch is slated for October aboard a United Launch Alliance Delta rocket from Cape Canaveral Air Force Station.
(Editing by Kevin Gray and Cynthia Osterman)