| T-00:02.4 |
Engine start |
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Atlas booster and sustainer engines are ignited and undergo checkout prior to liftoff. |
|
| T+00:00 |
Launch |
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Rocket lifts off and begins a vertical rise away from launch pad 36A at Cape Canaveral Air Station. |
|
| T+00:02 |
Roll Program |
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During vertical ascent, Atlas begins a 13-second roll maneuver to align itself with proper flight azimuth of 104 degrees. Following the roll, the vehicle begins open-loop pitch and yaw steering under control of the Centaur inertial guidance system. |
|
| T+02:44.7 |
Booster Engine Cutoff |
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BECO occurs when axial acceleration of 5.5 g is obtained. Sustainer engine provides the continued boost toward orbit for the Atlas rocket. |
|
| T+02:47.8 |
Jettison Booster Package |
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The bottom engine structure with the two booster engines is separated from the Atlas vehicle. |
|
| T+03:53.5 |
Jettison Payload Fairing |
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The 11-foot diameter aluminum payload fairing that protected the DSCS B8 satellite during launch is separated once heating levels drop to predetermined limits. |
|
| T+04:41.6 |
Sustainer Engine Cutoff |
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SECO is commanded once minimum residual propellant is sensed inside the Atlas booster stage. |
|
| T+04:43.6 |
Atlas/Centaur Separation |
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Two seconds after the Atlas sustainer engine shuts down, the Atlas booster stage separates from the Centaur upper stage. |
|
| T+05:00.1 |
Centaur 1st Main Engine Start |
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MES 1, the longer of the two Centaur firings begins to inject the upper stage and DCSC B8 spacecraft into a low-altitude parking orbit around Earth. Guidance steering in the burn will result in an inclination of 29.3 degrees. |
|
| T+10:07.1 |
Centaur Main Engine Cutoff |
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MECO 1 occurs the Centaur engines are shutdown, arriving in a planned 80 x 485 nautical mile orbit. The vehicle begins a coast period over the mid-Atlantic before arriving at the required location in space for the second burn. |
|
| T+22:17.0 |
Centaur 2nd Main Engine Start |
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MES 2 occurs over the Atlantic Ocean near the African Ivory Coast as the rocket passes over the equator. The burn accelerates the vehicle and satellite into the required subsynchronous transfer orbit. |
|
| T+23:43.4 |
Centaur Main Engine Cutoff |
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At the point of MECO 2, the Centaur/DSCS B8 vehicle should be in the required transfer orbit. |
|
| T+25:17.4 |
Start Spinup |
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The Centaur's reaction control system thrusters initiate the required spinup of the DSCS B8 satellite to 4.7 rpm. |
|
| T+26:38.4 |
Spacecraft Separation |
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The Defense Satellite Communications System B8 spacecraft is released into orbit from the Centaur upper stage to complete the AC-138 launch. |
