September 26, 2017

Launch timeline for Ariane 5’s flight with Hellas-Sat 3/Inmarsat S EAN and GSAT 17

An Ariane 5 rocket will make its fourth flight of the year Wednesday, hauling two communications satellites into orbit for Inmarsat, Hellas-Sat and India’s space agency.

The nearly 180-foot-tall (55-meter) launcher will blast off from Kourou, French Guiana, at 2059 GMT (4:59 p.m. EDT; 5:59 p.m. French Guiana time) with the Hellas-Sat 3/Inmarsat S EAN and GSAT 17 communications satellites.

Made in France by Thales Alenia Space and in India by the Indian Space Research Organization, respectively, Hellas-Sat 3/Inmarsat S EAN and GSAT 17 will ride aboard the Ariane 5 in a dual-payload stack. The larger of the two satellites, Hellas-Sat 3/Inmarsat S EAN, will deploy first, followed by separation of GSAT 17 around 42 minutes after liftoff.

The rocket will target an orbit ranging from 155 miles (250 kilometers) to 22,236 miles (35,786 kilometers), with a tilt of 3 degrees to the equator.

Date source: Arianespace

T-0:00:00: Vulcain 2 ignition

The Ariane 5's first stage Vulcain 2 main engine ignites as the countdown clock hits zero, throttling up to about 300,000 pounds of thrust and undergoing a computer health check before liftoff.
The Ariane 5’s first stage Vulcain 2 main engine ignites as the countdown clock hits zero, throttling up to about 300,000 pounds of thrust and undergoing a computer health check before liftoff.

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

The Ariane 5's two solid rocket boosters ignite seven seconds later, each generating more than 1.3 million pounds of thrust.
The Ariane 5’s two solid rocket boosters ignite seven seconds later, each generating more than 1.3 million pounds of thrust, to push the vehicle into the sky from the ELA-3 launch pad.

T+0:00:50: Mach 1

The Ariane 5 rocket surpasses the speed of sound, heading east over the Atlantic Ocean.
The Ariane 5 rocket surpasses the speed of sound, heading east over the Atlantic Ocean.

T+0:02:19: Solid rocket boosters jettisoned

After each consuming 240 metric tons, or about 530,000 pounds, of pre-packed propellant, the solid rocket boosters are jettisoned.
After each consuming 240 metric tons, or about 530,000 pounds, of pre-packed propellant, the solid rocket boosters are jettisoned.

T+0:03:17: Payload fairing jettisoned

The Ariane 5's payload fairing, made in Switzerland by Ruag Space, releases in a clamshell-like fashion once the rocket flies above the denser, lower layers of Earth's atmosphere.
The Ariane 5’s 17.7-foot-diameter (5.4-meter) payload fairing, made in Switzerland by Ruag Space, releases in a clamshell-like fashion once the rocket flies above the denser, lower layers of Earth’s atmosphere.

T+0:08:52: Vulcain 2 shutdown

The Ariane 5’s core stage Vulcain 2 main engine shuts down after consuming 175 metric tons (385,000 pounds) of cryogenic liquid hydrogen and liquid oxygen propellants.

T+0:08:58: Stage separation

The Ariane 5’s first and second stages separate. The 98-foot-long (30-meter) first stage will fall into the Atlantic Ocean near the Gulf of Guinea off the west coast of Africa.

T+0:09:02: HM7B ignition

The Ariane 5’s upper stage HM7B engine ignites for a 15-minute, 54-second burn to place the Hellas-Sat 3/Inmarsat S EAN and GSAT 17 satellites into geostationary transfer orbit. The HM7B engine burns liquid hydrogen and liquid oxygen, and generates more than 14,000 pounds of thrust.

T+0:25:04: HM7B shutdown

The HM7B engine shuts down after placing the Hellas-Sat 3/Inmarsat S EAN and GSAT 17 satellites into geostationary transfer orbit with a low point of 155 miles (250 kilometers), a high point of 22,236 miles (35,786 kilometers), and an inclination of 3 degrees to the equator.

T+0:28:17: Hellas-Sat 3/Inmarsat S EAN separation

The Hellas-Sat 3/Inmarsat S EAN satellite, riding in the upper position on the Ariane 5’s dual-payload stack, deploys to begin an 17-year mission supporting the European Aviation Network for Inmarsat and broadcasting television and other services across Europe, Africa and the Middle East for Hellas-Sat.

T+0:29:58: Sylda 5 separation

The Sylda 5 dual-payload adapter structure jettisons from the Ariane 5 upper stage, revealing the GSAT 17 spacecraft for deployment.

T+0:41:47: GSAT 17 separation

The GSAT 17 spacecraft is released from the Ariane 5 launcher to provide communications and data relay services over India.

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