Ariane 5 - Flight VA208
The 208th Ariane Mission – VA208 – will deliver two commercial communications satelites to their desired orbits. It will be the 64th launch of the powerful Ariane 5. The launch site will be ELA-3 at the Guiana Space Center, French Guiana. It will be the 4th Ariane 5 launch of 2012.
Intelsat 20 is one of the most powerful FSS (Fixed Satellite Services) Communications Satellites ever built. It was manufactured by Space Systems Loral of Palo Alto, California, and is based on the company's flexible LS-1300 Satellite Bus. The vehicle has a launch mass of 5,800 Kilograms. The satellite's operator is Intelsat, Luxembourg. The Satellite is equipped with a powerful communications Payload consisting of 24 C-Band Transponders, 54 Ku-Band Transponders and a single Ka-Band Transponder. The Payload is optimized for high-power distribution of video, voice and data network services. The Vehicle has two deployable solar arrays and on-board batteries for power generation and storage. The vehicle is equipped with a R-4D Main Engine as part of its propulsion system. R-4D has a dry mass of 3.76 Kilograms and is 0.55 meters in length with a nozzle diameter of 0.3 meters. It provides 489 Newtons of thrust burning Monomethylhydrazine and Mixed Oxides of Nitrogen as propellants. The engine has no burn limitations; its longest demonstration burn was 200 minutes in duration. The Intelsat 20 spacecraft will replace Intelsat 7 and 10 which are co-located at an Orbital Position of 68.5 East Longitude. From there, Intelsat 20 will cover Europe, Africa and the Middle East. The Spacecraft will operate for at least 15 years.
Hylas 2 is a Commercial Communications Satellite that was manufactured by Orbital Sciences Corporation based in Dulles, Virginia, and will be operated by Avanti Communications Group, London. The Satellite is based on Orbital's Star-2.4 Burs and has a liftoff mass of about 3,080 Kilograms. The Spacecraft hosts a payload of 24 active Ka-Band Transponders and six gateway beams. Total Payload power is about 5 Kilowatts. Ka-and spot beam technology provides high-speed delivery of data to end-user applications such as corporate networking, broadband Internet access, business continuity services and video distribution. The vehicle has two deployable antennas with six antenna surfaces and one steerable Nadir antenna which provides a single steerable Ka-Band Spot Beam which can provide coverage for any location in the satellite's field of view. The Spacecraft is outfitted with two deployable solar arrays and batteries, is three-axis stabilized and has an on-orbit servicing life of 15 years. It propulsion system features an IHI BT-4 Main Engine.
BT-4 was developed by IHI Aerospace, Japan and has a dry mass of 4 kilograms and a length of 0.65 meters. The engine provides 450 Newtons of Thrust and uses Hydrazine and mixed Oxides of Nitrogen as propellants. Hylas 2 will operate from an orbital position of 34 degrees West in Geostationary Orbit providing coverage of Northern and Southern Africa, Eastern Europe and the Middle East.
The Countdown for a Launch of the Ariane 5 Rocket begins 11 hours and 30 minutes before the launch window opens. At L-7:30 final electrical checks will be made before Fueling starts just under 5 hours to liftoff. 90 Minutes into LOX and LH2 Tanking, the Vulcain Main Engine is being chilled down by the supercold propellants. 1 hour and 10 minutes prior to launch, final checks of all communication connections and telemetry links are conducted to ensure all Ground Tracking Stations are ready to support the mission. The Vehicle will be placed in a stable configuration for T-7 Minutes and Holding. The Launcher can remain in this configuration throughout the launch window. At T-7 Minutes and Counting, the Synchronized Sequence begins. Computers are watching all parameters of the vehicle and ground support equipment as final reconfigurations are made to put the Ariane in a launch configuration. Should any system show an off-nominal performance, the Computers will automatically recycle all systems to their T-7-Configuration to back out of the automated sequence. 4 Minutes prior to launch, all tanks of the first and second stage are being pressurized for flight. 1 Minute before T-0, the vehicle switches to onboard power. 30 Seconds before Ignition, Water begins flowing into the Flame Trenches. Hydrogen aspiration of the Vulcain engine starts 18 seconds before it is ignited. The Cryogenic arms that are used for critical connections including fuel lines are retracted. 4 seconds before the Ignition Sequence commences, the Handoff to Ariane’s onboard computers occurs and the Guidance System enters its flight mode one second later.
At T-0, the Vulcain Engine Ignition Sequence begins. Three pyrotechnic devices are used to ignite the main engine which reaches flight thrust at T+4.5 seconds. Engine performance is being monitored before the Solid Rocket Boosters are ignited at T+7.05 seconds. Liftoff occurs just a quarter of a second later. The two Solid Rocket Boosters provide 92% of total thrust at blastoff. The launcher climbs vertically for 6 seconds before the pitch maneuver begins which puts the rocket into the proper trajectory that is required to reach the targeted Main Engine Cutoff point.
_After 2 minutes and 21 seconds of powered flight, the SRBs burn out and are jettisoned to fall back to Earth and into the Atlantic Ocean. Immediately after SRB jettison, the onboard computers calculate the precise trajectory that is required to recover from minimal transients that are nominal for the SRB Phase. That course correction is conducted in real time by swivalling the main engine. The next Event is Payload Fairing Jettison. The Fairing is used to protect the Payloads from thermal loads during atmospheric flight. When heat levels are at an acceptable level, the fairing is jettisoned by pyrotechnically initiated separation tubes. Separating the fairing as early as possible increases ascent performance. At 9 minutes into the flight, the Vulcain Engine shuts down for first stage cutoff. Stages #1 and #2 separate from each other and the second stage with its HM-7B engine continue powered flight after the engine ignites. The first stage falls back to Earth and impacts off the coast of Africa in the Gulf of Guinea. The second stage will make its first burn before final engine cutoff. Afterwards, the stage re-orients itself to the proper attitude to release the first payload. When the first Spacecraft Separation is successful, the coast phase continues with more orientation maneuvers and the separation of the Sylda 5. This is a fairing like object that is used to install two payloads on top of the rocket. The first payload is mounted atop the Sylda and the second satellite is hidden beneath it until the first payload is released. With Sylda Separation, the path is clear to jettison the second and final payload into its targeted orbit. The second stage continues its mission for several minutes during which it performs reorientation maneuvers and avoidance firings. After second stage passivation, Ariane’s mission is complete. The two satellites will then be in a geostationary transfer orbit that will be optimized when the spacecraft fire their individual engines to reach a precise position.
|Time||Event||Altitude (km)||Velocity (m/s)|
|0:00:00.00||Vulcain Engine Ignition Sequence||0||0|
|0:00:07.05||Solid Rocket Booster Ignition||0||0|
|0:02:21.00||SRB Burnout and Jettison||67.100||2009.0|
|0:03:16.00||Payload Fairing Jettison||107.500||2258.0|
|0:08:12:00||Acquisition by Natal Tracking Station||157.900||5782.0|
|0:08:57.00||Core Stage shutdown||155.600||6915.0|
|0:09:07.00||2nd Stage Ignition||155.600||6943.0|
|0:13:53.00||Acquisition by Ascension Tracking Station||141.100||7628.0|
|0:18:29.00||Acquisition by Libreville Tracking Station||173.800||8328.0|
|0:23:12.00||Acquisition by Malindi Tracking Station||413.500||9033.0|
|0:25:27.00||Second Stage Shutdown||658.000||9352.0|
|0:28:01.00||Intelsat 20 Release||1049.000||9028.0|
|0:34:17.00||HYLAS 2 Release||2345.000||8103.0|
|0:44:32.00||Ariane 5 - End of Mission||4906.000||6720.0|