#Atlas 5/OSIRIS-REx launch timeline

Follow the Atlas 5 rocket’s ascent from Cape Canaveral’s Complex 41 launch pad to send NASA’s OSIRIS-REx on an interplanetary trajectory to intercept Asteroid Bennu and bring back a pristine sample. Launch is scheduled for Thursday at 7:05 p.m. EDT (2305 GMT).

(Editor’s note: Times will vary slightly depending on when liftoff occurs during the two-hour daily launch window.)

T+00:01.1: LiftoffAV-008
The United Launch Alliance Atlas 5 vehicle, designated AV-067, will lift off and begin a vertical rise away from Complex 41 at Cape Canaveral Air Force Station, Florida.

T+00:57: Mach 1 and Max Q
The Atlas rocket achieves Mach 1 some 57 seconds into the flight, then passes through the region of maximum dynamic pressure at 69 seconds.

T+02:19 Jettison SRB
Having burned out of propellant approximately 50 seconds earlier, the spent solid rocket booster is jettisoned once dynamic pressure conditions are satisfied.

T+04:03: 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+04:09: 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+04:19: Centaur Ignition No. 1
The Centaur RL10 engine ignites for the longer of the two upper stage firings. This burn will inject the Centaur stage and OSIRIS-REx into an Earth parking orbit.

T+04:27: Nose Cone Jettison
The two-piece, 14-foot-diameter payload fairing that protected the OSIRIS-REx spacecraft during the atmospheric ascent is separated to reveal the satellite to space.

T+12:23: Centaur Engine Cutoff No. 1
The Centaur engine shuts down after arriving in its planned temporary orbit around the Earth. The vehicle enters a brief coast period before reaching at the required location in space for the second burn.

T+33:48: Centaur Ignition No. 2
The Centaur re-ignites to propel OSIRIS-REx on the outbound leg of its journey to Asteroid Bennu.

T+40:39: Centaur Engine Cutoff No. 2
At the conclusion of its second firing, the Centaur will have delivered the necessary velocity for OSIRIS-REx to achieve an Earth-escape trajectory.

T+55:39: Spacecraft Separation
NASA’s OSIRIS-REx asteroid sample return mission is released from the Centaur upper stage to begin its solo flight to Bennu, completing the AV-067 launch.

See earlier OSIRIS-REx coverage.

Our Atlas archive.

from Spaceflight Now ift.tt/2cdigDG

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