June 21, 2018

Falcon 9 launch timeline with SES 12

SpaceX’s Falcon 9 rocket is set for liftoff from Cape Canaveral on Monday, heading due east over the Atlantic Ocean to deliver the SES 12 communications satellite into orbit around 32 minutes later.

The 229-foot-tall (70-meter) rocket is poised for launch from pad 40 at Cape Canaveral Air Force Station in Florida at 12:29 a.m. EDT (0429 GMT) Monday at the opening of a four-hour launch window.

Perched atop the rocket is the SES 12 communications satellite, a spacecraft manufactured by Airbus Defense and Space and propelled by plasma thrusters, eliminating the need for large conventional liquid fuel tanks.

SES 12 weighs 11,867 pounds (5,383 kilograms) with its supply of xenon propellant for the electric thrusters, while a satellite with similar capability would weigh up to 10 metric tons if it carried the customary hydrazine and nitrogen tetroxide propellants used by conventional spacecraft.

The weight savings allowed SES to fit SES 12 on a smaller, less expensive rocket, and permitted engineers to combine two communications missions into one spacecraft. SES 12 will provide direct-to-home television broadcasts, video and data relay services, and broadband connectivity across the Middle East, the Asia-Pacific, and Australia during its 15-year mission.

SES 12 will use its plasma jets to climb into a circular geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator after deployment from the Falcon 9 rocket in an elliptical transfer orbit.

The Falcon 9 rocket launching SES 12 will use a previously-flown “Block 4” version first stage refurbished after a September 2017 mission with the U.S. Air Force’s X-37B spaceplane. The first stage will not be recovered on the SES 12 mission.

The newly-built upper stage includes upgrades introduced by SpaceX for the “Block 5” version of the Falcon 9 rocket.

The timeline below outlines the launch sequence for the Falcon 9 flight with SES 12.

Data source: SpaceX

T-0:00:00: Liftoff

After the rocket’s nine Merlin engines pass an automated health check, hold-down clamps will release the Falcon 9 booster for liftoff from Complex 40.
After the rocket’s nine Merlin engines pass an automated health check, hold-down clamps will release the Falcon 9 booster for liftoff from pad 40.

T+0:01:13: Mach 1

The Falcon 9 rocket reaches Mach 1, the speed of sound.
The Falcon 9 rocket reaches Mach 1, the speed of sound, as the nine Merlin 1D engines provide more than 1.7 million pounds of thrust.

T+0:01:21: Max Q

The Falcon 9 rocket reaches Max Q, the point of maximum aerodynamic pressure.
The Falcon 9 rocket reaches Max Q, the point of maximum aerodynamic pressure.

T+0:02:44: MECO

The Falcon 9’s nine Merlin 1D engines shut down.
The Falcon 9’s nine Merlin 1D engines shut down.

T+0:02:48: Stage 1 Separation

The Falcon 9’s first stage separates from the second stage moments after MECO.
The Falcon 9’s first stage separates from the second stage moments after MECO.

T+0:02:55: First Ignition of Second Stage

The second stage Merlin 1D vacuum engine ignites for an approximately 6-minute burn to put the rocket and SES 9 into a preliminary parking orbit.
The second stage Merlin 1D vacuum engine ignites for a six-minute burn to put the rocket and SES 12 into a preliminary parking orbit.

T+0:03:27: Fairing Jettison

The 5.2-meter (17.1-foot) diameter payload fairing jettisons once the Falcon 9 rocket ascends through the dense lower atmosphere. The 43-foot-tall fairing is made of two clamshell-like halves composed of carbon fiber with an aluminum honeycomb core.
The 5.2-meter (17.1-foot) diameter payload fairing jettisons once the Falcon 9 rocket ascends through the dense lower atmosphere. The 43-foot-tall fairing is made of two clamshell-like halves composed of carbon fiber with an aluminum honeycomb core.

T+0:08:25: SECO 1

The second stage of the Falcon 9 rocket shuts down after reaching a preliminary low-altitude orbit. The upper stage and SES 9 begin a coast phase scheduled to last more than 18 minutes before the second stage Merlin vacuum engine reignites.
The second stage of the Falcon 9 rocket shuts down after reaching a preliminary low-altitude orbit. The upper stage and SES 12 begin a coast phase scheduled to last nearly 18 minutes before the second stage Merlin vacuum engine reignites.

T+0:26:06: Second Ignition of Second Stage

The Falcon 9's second stage Merlin engine restarts to propel the SES 9 communications satellite into a supersynchronous transfer orbit.
The Falcon 9’s second stage Merlin engine restarts to propel the SES 12 communications satellite into a supersynchronous transfer orbit.

T+0:27:13: SECO 2

The Merlin engine shuts down after a short burn to put the SES 10 satellite in the proper orbit for deployment.
The Merlin engine shuts down after a short burn to put the SES 12 satellite in the proper orbit for deployment.

T+0:32:51: SES 12 Separation

The SES 9 satellite separates from the Falcon 9 rocket in an orbit with a predicted high point of about 39,300 kilometers (24,400 miles), a low point of 290 kilometers (180 miles) and an inclination of 28 degrees. Due to the decision to burn the second stage nearly to depletion, there is some slight uncertainty on the orbital parameters based on the exact performance of the launcher.
The SES 12 satellite separates from the Falcon 9 rocket in a geostationary transfer orbit with a perigee of 182 miles (294 kilometers) and a targeted apogee of around 36,357 miles (58,511 kilometers), with an apogee range plus or minus approximately 300 miles (500 kilometers).

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