The GPS IIR-20 (M) launch is the Space and Missile Systems Center's 60th consecutive launch success, and the third for the Launch and Range Systems Wing in 2009. The GPS satellite was join the constellation of 31 operational satellites on-orbit providing global coverage and increased overall performance of GPS services to users worldwide. The GPS IIR-M satellites offer a variety of enhanced features for GPS users such as two new military signals for improved accuracy, enhanced encryption, anti-jamming capabilities and a second civil signal to provide dual frequency capability and improve resistance to interference. GPS IIR-20(M) was assumed plane B, slot 2 position replacing space vehicle number (SVN) 30. The Air Force is launching its last GPS IIR-M satellite in March 2009 from Cape Canaveral Air Force Station at the start of a window running from 08:34 to 08:49 GMT.
The Delta II will fly in the 7925 configuration, with an Extra-Extended Long Tank Thor first stage, nine strap-on GEM 40 solid rocket motors, a Delta-K second stage, and a Star 48B upper stage. The payload fairing is the standard configuration, with a diameter of 2.9 meters, or 9.5 feet.
The first stage is powered by an RS-27A main engine and two verniers, which will ignite about two seconds before launch. At lift-off, six of the nine SRMs will also light. These first SRMs will burn out and separate a little over a minute after launch, seconds before the remaining three ignite for their minute-long burn.
Just under four and a half minutes after launch, the first stage main engine will shut down, followed by the verniers. The first stage will then separate, and the vehicle will coast for five seconds before the AJ-10-118K engine of the second stage ignites for its first burn. Separation of the payload fairing will occur about twenty seconds later.
The first burn will last for six minutes and twelve seconds, before shutting down and initiating a coast phase that will last for a little under fifty two minutes. Following this, it will restart for forty two seconds, and then initiate third stage spin-up.
Subsequently, the second and third stages will separate, and the solid-fuelled third stage will ignite for an eighty-seven second burn. Once the stage has burnt out, there will be another two minutes of coasting, before the spacecraft separates.
From lift-off to payload separation, the launch will last about sixty-eight minutes, and will leave the satellite in a 193 by 20,370 kilometre orbit, with an inclination of 40 degrees. The spacecraft will then use its onboard propulsion system to reach its operational medium Earth orbit.
[Reference: NASA.space.flight ]