June 18, 2018

Atlas 5/GOES-S launch timeline

This is the launch timeline to be followed by the Atlas 5 rocket’s ascent into orbit from Cape Canaveral with the GOES-S weather satellite. Launch is scheduled for Thursday during a two-hour window opening at 5:02 p.m. EST (2202 GMT).

The 197-foot-tall rocket will arc to the east from Florida’s Space Coast on its second flight of the year. It will be the 76th Atlas 5 launch overall since United Launch Alliance’s workhorse rocket debuted in August 2002.

The timeline below ends with the conclusion of the primary mission, the deployment of the GOES-S satellite into an elliptical geostationary transfer orbit.

Follow live coverage of the countdown and launch in our Mission Status Center.

A video overview of the Atlas 5 launch sequence also describes the major milestones on the GOES-S mission.

T+0:00:01.1: 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+0:00:35.2: Mach 1

Riding 2.1 million pounds of thrust from its RD-180 main engine and four solid rocket boosters, the Atlas 5 exceeds the speed of sound.

T+0:00:47.1: Max-Q

The Atlas 5 rocket passes through the region of maximum dynamic pressure during ascent through the lower atmosphere.

T+0:01:50.3: Jettison SRBs

Having burned out of propellant approximately 20 seconds earlier, the four spent Aerojet Rocketdyne-built solid rocket boosters are jettisoned once dynamic pressure conditions are satisfied.

T+0:03:29.9: Nose Cone Jettison

The Atlas 5 rocket’s payload fairing, made in Switzerland by Ruag Space, is jettisoned in a clamshell-like fashion once external heating levels drop below predetermined limits after climbing through the dense lower atmosphere. The Forward Load Reactor deck that connected the payload fairing’s structure to the Centaur upper stage is released five seconds after the shroud’s jettison.

T+0:04:21.9: 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+0:04:27.9: 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+0:04:37.9: Centaur Ignition 1

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

T+0:12:11.1: Centaur Cutoff 1

The Centaur engine shuts down after arriving in a planned low-Earth parking orbit. The vehicle enters a 10-minute coast period before arriving at the required location in space for the second burn.

T+0:22:38.4: Centaur Ignition 2

The Centaur re-ignites to accelerate the payload into a highly elliptical transfer orbit from the parking altitude achieved earlier in the launch sequence. This burn lasts five-and-a-half minutes.

T+0:28:09.3: Centaur Cutoff 2

The second Centaur firing places the GOES-S satellite into an elliptical transfer orbit stretching more than 20,000 miles above Earth, beginning a three-hour coast period for the mission’s final orbital adjustment maneuver.

T+3:28:07.9: Centaur Ignition 3

After a three-hour coast, the Centaur’s RL10 engine reignites for a roughly 95-second firing to raise the GOES-S satellite’s perigee, or orbital low point, and reduce its inclination closer to the equator.

T+3:29:42.3: Centaur Cutoff 3

The powered phase of flight is concluded as the Centaur reaches the planned geosynchronous transfer orbit with a perigee, or low point, of 5,104 miles (8,215 kilometers), an apogee, or high point, of 21,926 miles (35,286 kilometers), and an inclination of 9.52 degrees.

T+3:32:31.3: GOES-S Separation

The Geostationary Operational Environmental Satellite-S, GOES-S, spacecraft deploys from the Centaur upper stage to begin its 15-year weather monitoring mission.

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