Timeline for Ariane 5’s launch of Sky Muster 2 and GSAT 18

October 4, 2016 Stephen Clark

A communications satellite to broadcast high-speed Internet to remote parts of Australia and a new platform to beam television and multimedia programming across India are fastened to the top of an Ariane 5 rocket for launch Wednesday.

Standing nearly 180 feet (55 meters) tall, the Ariane 5 is scheduled to lift off from Kourou, French Guiana, at 2030 GMT (4:30 p.m. EDT; 5:30 p.m. French Guiana time) Wednesday. The launch will mark the 88th Ariane 5 flight since 1996, and the launcher’s fifth mission this year.

Liftoff was delayed from Tuesday due to unfavorable high-altitude winds.

The Sky Muster 2 satellite, built by Space Systems/Loral and weighing 14,120 pounds (6,405 kilograms) at launch, is the heavier of the two spacecraft aboard the Ariane 5 rocket. GSAT 18, built and owned by the Indian Space Research Organization, weighs 7,504 pounds (3,404 kilograms) with its propellant tanks full.

The rocket will target an orbit ranging from 155 miles (250 kilometers) to 22,236 miles (35,786 kilometers), with a tilt of 6 degrees to the equator.

Once the Ariane 5 releases Sky Muster 2 and GSAT 18, the upper stage will conduct experimental maneuvers to collect data that will be used in development of the next-generation Ariane 6 rocket.

The Ariane 5 upper stage’s HM7B engine cannot be restarted in space, but European industry is developing a new hydrogen-fueled engine to fly on the Ariane 6 launcher beginning in 2020. The new Vinci engine will be re-ignited during flight.

The demonstration on this flight is expected to test re-pressurization of the upper stage’s liquid hydrogen and liquid oxygen tanks, propellant settling, and engine chilldown procedures in orbit.

Arianespace and Airbus Safran Launchers, the new joint venture between rocket-builder Airbus Defense and Space and French engine-maker Safran, plan to conduct the experiments on three Ariane 5 launches to validate engineering models for the development of the Vinci engine.

The first such “demo flight” experiment of the upper stage occurred in May 2015, followed by additional tests on a launch in March. This is the third and final demo flight experiment.

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+0:02:23: 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+0:03:16: 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+0:08:54: 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.
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+0:09:00: 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.
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+0:09:04: HM7B ignition

The Ariane 5's upper stage HM7B engine ignites for a 16-minute, 9-second burn to place the Sky Muster 2 and GSAT 18 satellites into geostationary transfer orbit. The HM7B engine burns liquid hydrogen and liquid oxygen, and generates more than 14,000 pounds of thrust.
The Ariane 5’s upper stage HM7B engine ignites for a 16-minute, 27-second burn to place the Sky Muster 2 and GSAT 18 satellites into geostationary transfer orbit. The HM7B engine burns liquid hydrogen and liquid oxygen, and generates more than 14,000 pounds of thrust.

T+0:25:17: HM7B shutdown

The HM7B engine shuts down after placing the Sky Muster 2 and GSAT 18 satellites into a 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 6 degrees to the equator.
The HM7B engine shuts down after placing the Sky Muster 2 and GSAT 18 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 6 degrees to the equator.

T+0:28:26: Sky Muster 2 separation

The Sky Muster 2 satellite, riding in the upper position on the Ariane 5's dual-payload stack, deploys to begin a 15-year mission providing high-speed Internet for Australia's National Broadband Network.
The Sky Muster 2 satellite, riding in the upper position on the Ariane 5’s dual-payload stack, deploys to begin a 15-year mission providing high-speed Internet for Australia’s National Broadband Network.

T+0:30:47: Sylda 5 separation

The Sylda 5 dual-payload adapter structure jettisons from the Ariane 5 upper stage, revealing the GSAT 18 spacecraft for deployment.
The Sylda 5 dual-payload adapter structure jettisons from the Ariane 5 upper stage, revealing the GSAT 18 spacecraft for deployment.

T+0:32:33: GSAT 18 separation

The GSAT 18 satellite separates from the Ariane 5's upper stage to begin a 15-year mission for the Indian Space Research Organization.
The GSAT 18 satellite separates from the Ariane 5’s upper stage to begin a 15-year mission for the Indian Space Research Organization.

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