CAPE CANAVERAL -- Their services have permeated daily lives for countless millions of people, and now the latest Global Positioning System satellite is awaiting blastoff Thursday to bolster the navigation network.

Credit: Walter Scriptunas II See more images

Liftoff of the GPS 2F-6 spacecraft aboard a United Launch Alliance Delta 4 rocket from Cape Canaveral is planned for 8:08 p.m. EDT at the opening of an 18-minute window.

"Civilian users around the world use GPS for highly accurate time, location and velocity information. From navigation systems in vehicles to timing of most financial transactions, GPS has permeated into nearly every aspect of our lives," said Lt. Col. Dave Ashley, 5th Space Launch Squadron commander at the Cape.

Flying to the northeast and paralleling the eastern seaboard, the launch is timed to deliver the 3,400-pound satellite directly into Plane D of the navigation network 11,000 nautical miles above Earth.

"This satellite, officially designated as Space Vehicle 67, is also informally named Rigel after the brightest star in the Orion constellation," said Col. Steve Steiner, GPS Space Systems Division chief.

The Delta 4 vehicle stands 205 feet tall and produces 1.2 million pounds at launch with its hydrogen-fueled main engine and twin solid rockets.

The Delta 4 rocket and GPS satellite. Credit: ULA

"Delta 4 has been a workhorse, delivering numerous GPS satellites for the Air Force and the nation," said Ron Fortson, United Launch Alliance's director of mission management. "We are looking forward to another successful GPS launch."

It will be the 26th Delta 4 launch and the fifth carrying a GPS satellite. It will be ULA's fifth flight of the year and the 82nd overall.

The Delta's flight will last three hours and 15 minutes from liftoff until spacecraft separation, firing its cryogenic upper stage twice to achieve an initial transfer orbit and then reaching the circular GPS orbit tilted 55 degrees to the equator.

GPS 2F-6 will replace the aging spacecraft known as GPS 2A-23 in Plane D, Slot 4 of the constellation. The GPS 2A-23 satellite was launched aboard Delta 223 in October 1993. It will go into a reserve role in the network for the remainder of its useful life.

The $245 million GPS 2F-6 incrementally upgrades the constellation with improved accuracy, enhanced internal atomic clocks, better anti-jam resistance, a civil signal for commercial aviation and a longer design life, all features of the Boeing-built Block 2F series.

The GPS 2F-6 satellite. Credit: Boeing

This will be the sixth of 12 Block 2F spacecraft being built to form the backbone of the GPS fleet for the next 15 years. The full dozen satellites are due to be launched by mid-2016.

GPS satellites operate in Medium Earth Orbit and emit continuous navigation signals that allow users to find their location in latitude, longitude and altitude and determine time. The constellation features six orbital planes with multiple satellites flying in each.

Users around the globe rely on GPS every day, whether they know it or not. From the overt navigation assistance in transportation to the less obvious role in providing accurate timing stamps on banking transactions, the system developed to support U.S. military forces and their guided munitions has blossomed in the commercial marketplace.

For tips on taking pictures of the launch, see our photography guide.

For details on where the best spots are to see the launch, see the viewing guide.

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