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An Ariane 5 rocket will fire into the sky from French Guiana Thursday evening and deliver a record heavyweight payload to orbit less than an hour later.

The nearly 180-foot-tall (55-meter) launcher will blast off from Kourou, French Guiana, at 2345 GMT (7:45 p.m. EDT; 8:45 p.m. French Guiana time) on its third flight of the year with the ViaSat 2 and Eutelsat 172B communications satellite.

Made in California by Boeing and in France by Airbus Defense and Space, respectively, ViaSat 2 and Eutelsat 172B will ride aboard the Ariane 5 in a dual-payload stack. The larger of the two satellites, ViaSat 2, will deploy first, followed by separation of Eutelsat 172B around 41 minutes after liftoff.

The rocket will target an orbit ranging from 155 miles (250 kilometers) to 22,186 miles (35,706 kilometers), with a tilt of 6 degrees to the equator.

Date source: Arianespace

T-0:00:00: Vulcain 2 ignition

T+0:00:07: Solid rocket booster ignition and liftoff

T+0:00:50: Mach 1

T+0:02:21: Solid rocket boosters jettisoned

T+0:03:22: Payload fairing jettisoned

T+0:08:56: Vulcain 2 shutdown

T+0:09:02: Stage separation

T+0:09:06: HM7B ignition

T+0:25:27: HM7B shutdown

T+0:29:26: ViaSat 2 separation

T+0:31:55: Sylda 5 separation

T+0:41:47: Eutelsat 172B separation

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Follow Stephen Clark on Twitter: @StephenClark1.