Eutelsat Konnect (Eutelsat BB4A), GSAT-30 - Ariane 5 ECA (VA251) - Kourou ELA-3 - 15.01.2020, TBD

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https://spaceflightnow.com/2020/01/16/ariane-5-va-251-mission-status-center/

01/16/2020 23:17 Stephen Clark

The countdown officially commenced at 0942 GMT (5:42 a.m. EST), with clocks at the Guiana Space Center timed for a targeted liftoff at 2105 GMT (4:05 p.m. EST; 6:05 p.m. French Guiana time). The launch window extends for 105 minutes.

Electrical systems checks on the Ariane 5 began at 1132 GMT (6:32 a.m. EST).

Workers also put finishing touches on the launch pad, including the closure of doors, removal of safety barriers and configuring fluid lines for fueling. The flight program for today's launch was also be loaded into the rocket's computer.

After a weather status report, the launch team began the process to fuel the rocket shortly with super-cold liquid hydrogen and liquid oxygen propellants around 1627 GMT (11:27 a.m. EST). First, ground reservoirs and the rocket's helium tank were pressurized, then the fuel lines were chilled down to condition the plumbing for the flow of super-cold liquid hydrogen and liquid oxygen, which are stored at approximately minus 423 degrees Fahrenheit and minus 298 degrees Fahrenheit, respectively.

It was expected to take approximately two hours to fill the Ariane 5 core stage tanks.

A similar procedure for the Ariane 5's cryogenic upper stage commenced at 1737 GMT (12:37 p.m. EST).

Chilldown conditioning of the Vulcain 2 first stage engine began at 1747 GMT (12:47 p.m. EST), and a communications check between the rocket and ground telemetry, tracking and command systems was for 1950 GMT (2:50 p.m. EST).

A final weather briefing will come at T-minus 10 minues, and then the computer-controlled synchronized countdown sequence will begin seven minutes before launch to pressurize propellant tanks, switch to on-board power and take the rocket's guidance system to flight mode.

The Vulcain 2 engine will ignite as the countdown clock reaches zero, followed by a health check and ignition of the Ariane 5's solid rocket boosters seven seconds later to send the 1.7 million-pound launcher skyward.

Five seconds after blastoff, the rocket will begin pitching east from the ELA-3 launch pad, surpassing the speed of sound less than a minute into the mission. The Ariane 5's twin solid rocket boosters will jettison nearly two-and-a-half minutes after liftoff.

Once above the dense atmosphere, the launcher's payload fairing will fall away at an altitude of more than 70 miles — about 112 kilometers -- at Plus+3 minutes, 19 seconds. The Ariane 5's first stage will shut down 8 minutes, 33 seconds, after liftoff, followed moments later by stage separation and ignition of the hydrogen-fueled cryogenic HM7B upper stage engine.

The rocket's upper stage will fire more than 16 minutes, accelerating to a velocity of 21,000 mph, or more than 9.3 kilometers per second, to reach an orbit with a planned high point of 35,761 kilometers (22,220 miles), a targeted low point of 250 kilometers (155 miles) and an inclination of 6 degrees.

The release of the Eutelsat Konnect satellite will come first at Plus+27 minutes, 30 seconds.

Once Eutelsat Konnect is deployed, the Ariane 5 rocket's barrel-shaped Sylda 5 dual-payload adapter will be jettisoned at Plus+29 minutes.

GSAT 30 will separate from the lower portion of the payload stack at 38 minutes, 25 seconds.

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01/16/2020 23:25 Stephen Clark

Minus-40 minutes. The Ariane 5's first and second stages are fully loaded loaded with cryogenic liquid hydrogen and liquid oxygen propellants.

The 17.7-foot-diameter first stage's Vulcain 2 engine burns 149.5 metric tons, or about 329,000 pounds, of liquid oxygen and 25 metric tons, or about 55,000 pounds, of liquid hydrogen. The cryogenic upper stage's HM7B engine consumes about 14.7 metric tons, or more than 32,000 pounds, of oxygen and hydrogen.

The fluids are stored at super-cold temperatures and naturally boil off in the warm tropical atmosphere in French Guiana. More propellant is slowly pumped into the rocket for most of the countdown to replenish the cryogenic fuel.

The topping sequence ends in the final few minutes of the countdown as the fuel tanks are pressurized and the fueling system is secured.

Built by a consortium of European contractors led by Ariane Group's facility in Vernon, France, the Vulcain 2 engine generates up to 300,000 pounds of thrust during its 9-minute firing. It burns about 320 kilograms, or 705 pounds, of liquid oxygen and liquid hydrogen propellant per second.

The engine's nozzle has an exit diameter of 2.1 meters, or about 6.9 feet. It weighs more than 4,600 pounds and its liquid oxygen and liquid hydrogen turbopumps spin at 12,300 rpm and 35,800 rpm, respectively.

The Vulcain 2 replaced the Vulcain engine used on the initial version of the Ariane 5. The newer engine produces 20 percent more thrust.

The Ariane 5's upper stage is powered by an HM7B engine, a modified version of the HM7 engine used on the upper stage of the Ariane 4 rocket. The 364-pound HM7B engine is manufactured by Ariane Group in Ottobrunn, Germany.

The HM7B engine produces more than 14,500 pounds of thrust in vacuum.

The Ariane 5 configuration with a Vulcain 2 engine and HM7B-powered cryogenic upper stage is known as the Ariane 5 ECA.

The Ariane 5's twin solid rocket boosters are packed with propellant near the launch site in French Guiana before they are assembled and positioned on each side of the cryogenic core stage.

With the rocket now fully fueled for launch, the vehicle weighs 1.7 million pounds. At liftoff, the rocket produces 2.9 million pounds of thrust.

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01/16/2020 23:36 Stephen Clark

Minus-29 minutes. Some statistics on today's flight:

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• 251st launch of an Ariane rocket since 1979
  
• 315th Arianespace mission
  
• 107th launch of an Ariane 5 rocket since 1996
  
• 34th Eutelsat satellite launched by Arianespace
  
• 163rd Thales Alenia Space-built satellite launched by Arianespace
  
• 24th ISRO satellite launched by Arianespace
  
• 10th Inmarsat satellite launched by Arianespace
  
• 74th launch of an Ariane 5 ECA rocket since 2002
  
• 82nd flight of a Vulcain 2 engine
  
• 106th flight of an HM7B engine
  
• 92nd Ariane 5 launch targeting GTO
  
• 1st launch from the Guiana Space Center in 2020
  
• 1st Ariane 5 launch in 2020
  

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01/16/2020 23:56 Stephen Clark

Minus-10 minutes. The status board in the Jupiter control center is all green, indicating no problems at this point in the countdown.

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01/16/2020 23:59 Stephen Clark

Minus-7 minutes and counting. The synchronized sequence has started. Computers are now in control of this automated final phase of the launch countdown to prepare the rocket and ground systems for liftoff. There are three computers running the countdown - one aboard the Ariane 5 and two redundant computers at the launch complex.

The launch time is set for 2105:00 GMT (4:05:00 p.m. EST; 6:05:00 p.m. French Guiana time). Liftoff actually occurs even seconds later with ignition of the solid rocket boosters.

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01/17/2020 00:01 Stephen Clark

Minus-5 minutes. All status panel lights remain green, indicating no problems right now that could prevent blastoff.

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01/17/2020 00:03 Stephen Clark

Minus-2 minutes. The Vulcain main engine supply valves are being opened. And the ground valves for engine chilldown are being closed.

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