As the day dawned at Cape Canaveral this morning, another Delta 2 rocket darted into the sky on a satellite deployment mission. But this successful launch was remarkably different. Instead of bringing joy, there was deep sadness from the finality bought by the flight.

The breath-taking blastoff at 6:35 a.m. EDT, with the first hints of sunlight peeking over the horizon, began an hour-long trek to space on a flight that would mark the final satellite of its breed to fly, the final time the U.S. Air Force would use this venerable rocket and the final scheduled use of a launch pad in existence for decades.

Credit: Stephen Clark/Spaceflight Now SEE MORE IMAGES

The three stages of the booster did their jobs, delivering the Global Positioning System spacecraft into the prescribed orbit just like the dependable Delta 2 had done 47 previous times for the navigation network in the past 20 years.

The rocket carried the last bird in the current era of GPS satellites, capping a partnership between the Delta 2 and spacecraft builder Lockheed Martin that expanded and modernized the constellation.

The Air Force now says farewell to the Delta 2 after more than 50 flights, seeing no future need for the launcher. During an upheaval in U.S. policy following the Challenger tragedy, the military helped conceive the rocket as a means of transferring satellite launches from the space shuttle to unmanned boosters. The Delta 2 proved to be a workhorse, but newer rockets will serve the Air Force going forward.

Another step in upgrading GPS

GPS satellites fly about 11,000 nautical miles above the planet and emit continuous navigation signals that allow users to find their precise position in latitude, longitude and altitude and determine time. Originally built for the U.S. military, the GPS service has spread across the world as an indispensable commercial utility.

"You are starting to see it integrated into everything we do. This came from a vision from a small number of people that really were diligent to keeping it moving forward even in when most people didn't think it was anything but a toy," said Col. Dave Madden, commander of the Air Force's Global Positioning Systems Wing.

The GPS 2R-21 spacecraft will replace a long-lived satellite in the navigation constellation, taking over Plane E, Slot 3 occupied by the GPS 2A-26 craft launched in July 1996 that's lasted nearly twice its design life.

The new satellite is another in a series equipped with modernized features designed as a bridge from the current generation of GPS spacecraft to the future ones. The upgraded craft transmit additional signals and offer improvements aimed at greater accuracy, tougher resistance to interference and enhanced performance for users around the globe.

The new civilian signal removes navigation errors caused by the Earth's ionosphere. The military advancements will provide a more robust jam-resistant signal and enable better targeting of GPS-guided weapons in hostile environments.

"With the whole modernization program, we're increasing the number of signals which is providing exponential growth in the uses and the ability to make this world a better place, and also give our military an edge up on the battlefield," Madden said.

"It is fascinating how this program funded by the Department of Defense, and now even the civil Department of Transportation is providing support funding to it, to how it's significantly, in my mind, changed the world and made life better for everybody on the planet."

An artist's concept shows a GPS Block 2R satellite orbiting Earth. Credit: Lockheed Martin

There are 30 operational satellites in the GPS network today, well above the minimum 24 needed. GPS 2R-21 should be ready to begin service in a couple of weeks.

"The current GPS constellation has the most satellites and the greatest capability ever," Madden said.

The Boeing-made GPS 2F family of satellites should begin launching early next year and further improve what the system can do.

"GPS is the preeminent military space-based position, navigation and timing service supporting the warfighter and the growing needs of our global economy. We are committed to maintaining the current level of service while striving to improve the GPS system as we sustain it and as we modernize it into the future," Madden said.

Era of the Air Force Delta 2 is over

After 20 years and over 50 launches of the Delta 2 vehicle for the Air Force, this successful relationship between rocket and customer has reached the end.

"While we celebrate the tremendous success the Delta 2 rocket has provided the Air Force over the past many years, we are saddened to say goodbye to what we feel like is a very dear friend. The Delta 2 rocket provided the military a highly reliable and capable launch service that has directly contributed to our warfighting capability and national defense," said John Wagner, the mission director and chief technical director at the Space and Missile System Center's Launch and Range Systems Wing.

The Delta 2 was born to launch the GPS constellation, a last-minute change as the nation shifted its dependence away from the space shuttle following Challenger.

"In 1986 after the Challenger accident, the Air Force had to very quickly make some real-time decisions on spinning up its expendable, unmanned launch vehicle program because prior to that we were putting all of our satellites on the space shuttle. Very quick, we had to put together two programs in order to get us back flying," said Wagner.

The Delta 2 rocket soars toward the horizon during its launch this morning. Credit: Stephen Clark/Spaceflight Now

The Delta 2, Atlas 2 and Titan 4 rockets served the Air Force well, carrying out dozens of flights between 1989 and today. But now the U.S. military has retired its use of those vehicles, completing a major chapter of U.S. space launch history.

"We had to really scramble to recover, but we have had a tremendous amount of success on all those programs and allowed us to maintain our satellites and keep our constellation healthy," Wagner said. "While these programs were unfortunately birthed due to a tragedy, they have been a tremendous success for the nation and for our military."

Although the rockets proved to be reliable, the Air Force has transitioned to newer vehicles -- the Atlas 5 and Delta 4 -- that are meant to be versatile in launching a range of different payloads. The upcoming GPS 2F satellites, for example, will be delivered directly into their high orbits in contrast to the Delta 2 that placed its GPS payloads into a transfer orbit that required those satellites to perform a major altitude raising maneuver with a kick motor.

United Launch Alliance has seven more Delta 2 launches for NASA and commercial customers planned over the next few years, including five from Vandenberg Air Force Base in California and two at Cape Canaveral. The company also has five rockets available to sell.

"The Delta 2 workhorse will remain the medium class launch vehicle industry standard for years to come," said Jim Sponnick, ULA's vice president for the Delta Product Line.

The Air Force's 1st Space Launch Squadron that has overseen Delta 2 missions from Cape Canaveral's Complex 17 will be inactivated tomorrow. NASA will take over the site on October 1, a spokesman says, for its GRAIL lunar research mission scheduled to launch in 2011.

Today was the final planned use of pad 17A that's been around since the 1950s. Throughout the history of rocketry at the Cape, various versions of the Thor and Delta launchers have flown from the site. Since the overall Delta 2 program is throttling down, the two remaining flights on the East Coast manifest plan to use neighboring pad 17B.

Additional coverage for subscribers:
VIDEO: DELTA 2 ROCKET LAUNCHES AT SUNRISE PLAY | HI-DEF
VIDEO: THE GPS 2R-21 MISSION SUCCESSFULLY BEGINS PLAY
VIDEO: PAD 17A MOBILE SERVICE TOWER ROLLED BACK PLAY
VIDEO: HISTORY OF DELTA 2 AND GPS SATELLITES PLAY
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