A software and security update by Lockheed Martin will improve the U.S. Air Force's GPS ground station used to communicate with the current and legacy series GPS satellites, such as GPS 2R pictured above.

WASHINGTON — A United Launch Alliance Delta 2 rocket successfully launched the last of the U.S. Air Force’s GPS 2R-series positioning and navigation satellites Aug. 17 from Cape Canaveral Air Force Station, Fla.

Designated GPS 2R-21(M), the satellite also is the last of eight Lockheed Martin-built GPS 2R satellites that were modernized for better performance and reliability. Lockheed Martin Space Systems of Newtown, Pa., built 21 GPS 2R satellites in all.

Enhancements on the GPS 2R-M satellites include additional civil and military signals, higher signal power and better resistance to jamming, Lockheed Martin said in a press release Aug. 17. GPS 2R-21 (M) joins 18 GPS 2R satellites — including six of the modernized versions — in the Air Force’s 30-satellite GPS constellation.

The first of the GPS 2R satellites was destroyed in a 1997 Delta 2 launch failure, Lockheed Martin spokesman Steve Tatum said. A GPS 2R-M satellite launched in March is still in testing, he said. That satellite carries an additional payload intended to reserve frequencies to be used by future GPS craft. The payload, dubbed L5, has shown problems during testing; Tatum said the satellite is expected to be declared operational in October.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the spacenews.com Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...