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AC-202 launch timeline
SPACEFLIGHT NOW
Posted: March 8, 2004

T-00:02.73 Engine Start
Engine start The Russian-built RD-180 engine rumbles to life and builds to 74 percent thrust. A health check of eight engine parameters is performed by the rocket's onboard computer a half-second before liftoff.
T+00:00 Launch
Liftoff The Atlas 3A rocket lifts off from pad 36B at Cape Canaveral Air Force Station, Florida, marking the rocket family's 5th flight
T+00:02 Roll and Pitch Programs
Roll During the vertical ascent Atlas completes a 7-second roll maneuver to align itself with proper flight azimuth. Following the roll, the rocket begins a pitch-over maneuver with Centaur inertial guidance system in control of pitch and yaw programs.
T+00:06 Throttle Up
Throttle up The RD-180 engine is throttled up from its liftoff thrust of 74 percent to 92 percent after the rocket clears the launch pad 36B tower.
T+00:33 Throttle Down
Throttle down The RD-180 engine is throttled down to a thrust level of about 60 percent to ease the rocket through the dense lower atmosphere.
T+01:05 Through Max-Q
Transonic The rocket passes through maximum dynamic pressure and goes transonic. The RD-180 now throttles back up to its cruise setting of just over 80 percent thrust, ramping up to 5.5 g's.
T+02:52 Throttle Down
Throttle down To prepare for the upcoming engine shutdown, the RD-180 is once again throttled down, this time to 47 percent.
T+03:01.4 Booster Engine Cutoff
BECO The RD-180 engine is commanded to cut off once minimum residual propellant is sensed inside the Atlas booster stage.
T+03:07.4 Atlas/Centaur Separation
Atlas separation Six seconds after engine shutdown, the Atlas booster stage separates from the Centaur upper stage. Over the next 11 seconds, the Centaur liquid hydrogen and liquid oxygen systems are readied for engine ignition and the nozzle extension is deployed.
T+03:18.4 Centaur Engine Start
MES-1 MES 1, the longer of the two Centaur firings, begins to inject the upper stage and MBSAT communications satellite into a low altitude parking orbit around Earth.
T+03:26.4 Jettison Payload Fairing
Fairing separation The 14-foot diameter aluminum payload fairing that protected the MBSAT satellite during launch is separated once heating levels drop to predetermined limits.
T+12:39.4 Centaur Engine Cutoff
MECO-1 MECO 1 occurs when the single Centaur engine is shut down, with the rocket arriving in a planned parking orbit. The vehicle begins a coast period over the mid-Atlantic before arriving at the required location in space for the second burn.
T+22:57.7 Centaur Engine Re-start
MES-2 MES 2 occurs over the Atlantic Ocean between the African Ivory Coast and Ascension Island before the rocket passes just north of the equator. The burn accelerates the vehicle and satellite into the required geosynchronous transfer orbit.
T+26:03.3 Centaur Engine Cutoff
MECO-2 At the point of MECO 2, the Centaur with MBSAT should be in the required transfer orbit, completing the powered phase of the launch. Moments later, the stage begins aligning to the satellite separation attitude.
T+28:39.3 Spacecraft Separation
Spacecraft separation The MBSAT spacecraft to provide mobile communications for Japan and South Korea is released into orbit from the Centaur upper stage to complete the AC-202 launch.

Image and data source: Lockheed Martin






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