This is the ascent timeline to be followed by the United Launch Alliance Atlas 5 rocket in launching the Mobile User Objective System satellite No. 3 on Jan. 20 at 7:43 p.m. EST.
With the RD-180 main engine running, the five strap-on solid rocket boosters are lit as the Atlas 5 vehicle lifts off and begins a vertical rise away from Complex 41 at Cape Canaveral Air Force Station, Florida.
T+0:00:51.2: Max Q
T+01:52.2 Jettison SRBs
Having burned out of propellant approximately 20 seconds earlier, the spent solid rocket boosters are jettisoned to fall into the Atlantic Ocean. The separation event is staggered with two motors releasing first, then the others about 1.5 seconds later.
T+03:33.0 Nose Cone Jettison
The payload fairing that protected the MUOS 3 spacecraft during launch is separated once heating levels drop to predetermined limits after passage through the atmosphere. The Forward Load Reactor deck that supported the payload fairing’s structure to Centaur upper stage is released five seconds after the shroud’s jettison.
T+04:27.6 Main Engine Cutoff
T+04:33.6 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+04:43.6 Centaur Ignition 1
T+12:30.4 Centaur Cutoff 1
The Centaur engine shuts down after arriving in a planned low-Earth parking orbit of 90 by 340 nautical miles at 28 degrees inclination. The vehicle enters an 8-minute coast period before arriving at the required location in space for the second burn.
T+20:32.5 Centaur Ignition 2
T+26:18.7 Centaur Cutoff 2