Follow the unclassified portion of the Atlas 5 rocket’s ascent to space from Cape Canaveral’s Complex 41 launch pad with the U.S. National Reconnaissance Office’s NROL-61 satellite. Launch is scheduled for Thursday at 8:37 a.m. EDT (1237 GMT).
The United Launch Alliance Atlas 5 vehicle, designated AV-065, will lift off and begin a vertical rise away from Complex 41 at Cape Canaveral Air Force Station, Florida.
T+00:47: Mach 1 and Max Q
The Atlas rocket achieves Mach 1 some 47 seconds into the flight, then passes through the region of maximum dynamic pressure at 52 seconds.
T+02:09 Jettison SRBs
Having burned out of propellant approximately 40 seconds earlier, the spent solid rocket boosters are jettisoned once dynamic pressure conditions are satisfied.
T+04:10: Main Engine Cutoff
The RD-180 main engine completes its firing after consuming the load of RP-1 kerosene fuel and liquid oxygen supply in the Atlas first stage.
T+04:16: 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+04:26: Centaur Ignition No. 1
The Centaur RL10 engine ignites to inject the Centaur stage and NROL-61 spacecraft into orbit.
T+04:34: Nose Cone Jettison
The two-piece, 14-foot-diameter payload fairing that protected the NROL-61 craft during the atmospheric ascent is separated to reveal the satellite to space.
The mission now enters a news blackout to perform the orbit-shaping and payload deployment for the National Reconnaissance Office in secrecy.