September 22, 2019

Timeline: Atlas 5/SBIRS GEO Flight 3 ascent events


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This is the launch timeline to be followed by the Atlas 5 rocket’s ascent into orbit from Cape Canaveral with the SBIRS GEO Flight 3 satellite for U.S. military infrared reconnaissance. Launch is scheduled for Thursday at 7:46 p.m. EST (0046 GMT).

T+00:01.1 Liftoff

With the RD-180 main engine running, the Atlas 5 vehicle lifts off and begins a vertical rise away from Complex 41 at Cape Canaveral Air Force Station, Florida.

T+00:90.6: Max Q

The Atlas rocket, after breaking the sound barrier at 81 seconds, passes through the region of maximum dynamic pressure during ascent through the lower atmosphere.

T+04:03.2 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+04:09.2 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.

+04:19.2 Centaur Ignition 1

The Centaur RL10C-1 engine ignites for the first of two upper stage firings. This burn will inject the Centaur stage and SBIRS spacecraft into an initial parking orbit.

T+04:27.2 Nose Cone Jettison

The payload fairing that protected the SBIRS GEO Flight 3 spacecraft during launch is separated after passage through the atmosphere.

T+15:22.9 Centaur Cutoff 1

The Centaur engine shuts down after arriving in a planned low-Earth parking orbit. The vehicle enters a 9-minute coast period before arriving at the required location in space for the second burn.

T+25:00.1 Centaur Ignition 2

A final push by Centaur is ignited to raise the orbit’s low point and reduce orbital inclination for the SBIRS GEO Flight 3 spacecraft.

T+28:38.3 Centaur Cutoff 2

The powered phase of flight is concluded as the Centaur reaches the planned geosynchronous transfer orbit of 115 by 22,237 statute miles and inclined at 23.29 degrees.

T+43:48.3 Spacecraft Separation

The SBIRS GEO Flight 3 missile warning sentinel is released into orbit from the Centaur upper stage to complete the launch.

See earlier SBIRS GEO Flight 3 coverage.

Our Atlas archive.


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