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Rocket: Atlas 5 (AV-031)
Payload: AEHF 2
Date: May 4, 2012
Window: 2:42 to 4:42pm EDT (1842-2042 GMT)
Site: SLC-41, Cape Canaveral, Florida
Feed: SES 2, C-band, Transponder 21, 87° West

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Atlas/AEHF launch timeline
BY SPACEFLIGHT NOW
Posted: April 23, 2012


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T-00:02.7 Engine Start
The Russian-designed RD-180 main engine is ignited and undergoes checkout prior to launch.
T+00:01.1 Liftoff
The three strap-on solid rocket boosters are lit as the Atlas 5 vehicle, designated AV-031, lifts off and begins a vertical rise away from Complex 41 at Cape Canaveral Air Force Station, Florida.
T+01:56 Jettison SRBs
Having burned out of propellant approximately 25 seconds earlier, the spent solid rocket boosters are jettisoned to fall into the Atlantic Ocean.
T+03:34 Nose Cone Jettison
The payload fairing that protected the AEHF 2 spacecraft during launch is separated once heating levels drop to predetermined limits.
T+03:39 Forward Load Reactor Jettison
The Forward Load Reactor deck that supported the payload fairing's structure to Centaur upper stage is released seconds after the shroud's jettison.
T+04:18 Main Engine Cutoff
The RD-180 main engine completes its firing after consuming its kerosene and liquid oxygen fuel supply in the Atlas first stage.
T+04:24 Stage Separation
The Common Core Booster first stage of the Atlas 5 rocket separates from the Centaur upper stage. Over the next few seconds, the Centaur engine liquid hydrogen and liquid oxygen systems are readied for ignition.
T+04:34 Centaur Ignition 1
The Centaur RL10 engine ignites for the longer of the two upper stage firings. This burn will inject the Centaur stage and AEHF 2 spacecraft into a parking orbit.
T+13:57 Centaur Cutoff 1
The Centaur engine shuts down after arriving in a planned parking orbit. The vehicle enters a brief coast period lasting nearly 8 minutes before arriving at the required location in space for the second burn.
T+22:06 Centaur Ignition 2
The Centaur re-ignites over the equatorial Atlantic to accelerate the payload into geosynchronous transfer orbit from the parking achieved earlier in the launch sequence.
T+27:48 Centaur Cutoff 2
At the conclusion of its second firing, the Centaur will have delivered the AEHF 2 spacecraft into the targeted orbit with an apogee of 31,070 statute miles, perigee of 140 statute miles and inclination of 21 degrees.
T+51:11 Spacecraft Separation
The U.S. military's second Advanced Extremely High Frequency communications satellite is released into orbit from the Centaur upper stage to complete the AV-031 launch.

Data source: United Launch Alliance.

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