GPS modernised replacement satellites lifted on schedule

The Boeing Delta II 7925-9.5 rocket is the powerful and reliable workhorse of the satellite placement industry. It has a Boeing first stage booster powered by a Pratt & Whitney Rocketdyne RS-27A main engine and nine Alliant Techsystems (ATK) solid rocket boosters.

An Aerojet AJ10-118K engine powers the storable propellant restartable second stage.

A Thiokol Star-48B solid rocket motor sends the third stage prior to spacecraft deployment.

Blasting off at 2:50 p.m. EDT, Sept. 24th with a nine-and-a-half-foot-diameter Boeing payload fairing containing the second replacement GPS IIR-15 (M) spacecraft, this giant workhorse lifted off from Space Launch Complex 17A at Cape Canaveral Air Force Station, successfully delivered to orbit earlier today a replenishment Block IIR Global Positioning System (GPS) satellite for the U.S. Air Force.

These modernized GPS satellites incorporate improvements to provide :

1. Greater accuracy on the ground for users
2. Increased resistance to interference - i.e defence in space from attack

GPS provides military and civilian users three-dimensional position location data in longitude, latitude and elevation as well as precise time and velocity (across land, space) . The satellites orbit the Earth every 12 hours, emitting continuous navigation signals. The signals are so accurate, time can be figured to within one millionth of a second, velocity within a fraction of a mile-per-second and location to within 100 feet.