| 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. |
