US Air Force Launches Advanced GPS Satellite into Orbit
The U.S. Air Force's GPS IIF-9 satellite blasts off from Florida's Cape Canaveral Air Force Station atop a United Launch Alliance Delta 4 Heavy rocket on March 25, 2014.
Credit: ULA

The U.S. Air Force has launched an advanced new satellite to help upgrade the nation's Global Positioning System (GPS) constellation.

The GPS IIF-9 satellite blasted off atop a United Launch Alliance Delta IV rocket from Florida's Cape Canaveral Air Force Station Wednesday (March 25) at 2:36 p.m. EDT (1836 GMT).

"I'm elated with today's successful launch," Brig. Gen. Bill Cooley, director of the Global Positioning System Directorate at the Air Force's Space and Missile Systems Center, said in a statement. "The GPS constellation remains healthy, strong and robust, and in over 20 years since initial operational capability, GPS has never failed to deliver on its global positioning, navigation and timing commitments."

A United Launch Alliance Delta IV rocket launches the U.S. Air Force's new GPS IIF-9 navigation satellite into orbit from Cape Canaveral Air Force Station in Florida on March 25, 2015.
A United Launch Alliance Delta IV rocket launches the U.S. Air Force's new GPS IIF-9 navigation satellite into orbit from Cape Canaveral Air Force Station in Florida on March 25, 2015.
Credit: United Launch Alliance
The U.S. Air Force's GPS IIF-9 navigation satellite is seen on the ground before its March 25, 2015 launch. The satellite joined 30 other GPS satellites in orbit after its successful launch.
The U.S. Air Force's GPS IIF-9 navigation satellite is seen on the ground before its March 25, 2015 launch. The satellite joined 30 other GPS satellites in orbit after its successful launch.
Credit: United Launch Alliance

The IIF-9 spacecraft joins 30 other operational GPS satellites in Earth orbit. It should come into service about four to six weeks from now, Cooley said. 

GPS satellites fly in medium-Earth orbit (MEO), at an altitude of about 12,550 miles (20,200 kilometers). The constellation consists of 24 "core" spacecraft, plus a number of on-orbit spares to ensure redundancy and continuity of coverage.

The satellites in the network range widely in age. GPS IIF-9, for example, will likely replace a spacecraft that launched in August 1993. That older satellite is one of three members of the "IIA" series that remain operational.

The IIA satellites launched from 1990 through 1997. The GPS constellation also currently includes 12 operational "IIR" satellites, which blasted off from 1997 through 2004; seven "IIR(M)" craft, which took flight between 2005 and 2009; and, with the addition of the newly launched satellite, nine IIF vehicles.

The Air Force plans to launch a total of 12 GPS IIF satellites, with the last one currently scheduled to lift off in January 2016. (The next group to launch will be the GPS III block satellites, which are now being built.)

"A path forward is in work to modernize GPS, and the IIF capability plays a vital role, updating the GPS constellation and maintaining the high level of accuracy required by the GPS system," Cooley told reporters during a prelaunch news conference last Friday (March 20).

Compared to previous GPS satellites, the IIF spacecraft feature improved accuracy (thanks to advanced atomic clocks), better signal strength and quality, and more civilian bands, Air Force officials have said. The latest spacecraft line also has a 12.5-year design life, whereas that of the IIA, IIR and IIR(M) was 7.5 years.

Boeing builds the IIF satellites for the Air Force. Each spacecraft costs $122 million to build in year-2000 dollars, Cooley said.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.