Spaceflight Now

Ariane 5 set to launch Arab and South Korean satellites

Posted: June 21, 2010;
Updated June 22nd after rollout

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The next Ariane 5 rocket was rolled to the launch pad Tuesday at the Guiana Space Center in South America for Wednesday evening's planned blastoff carrying a pair of satellites for diverse purposes.

File image. Credit: Arianespace
Arianespace reported Monday's Launch Readiness Review gave consensus to proceed into the final preparations for Flight 195 with the Arabsat 5A communications spacecraft and South Korea's COMS satellite for communications, ocean-watching and weather forecasting.

The massive launcher's assembly process started in early March when the cryogenic main stage was erected and the twin solid rocket boosters were brought into position atop the mobile launching platform. The upper stage was attached a few days later.

The dual payloads sharing the ride into space were delivered to the launch site in mid-March from their manufacturing homes in Europe to undergo fueling and the pre-launch activities.

The Ariane was moved from its buildup hangar to the final assembly site in early June to receive the satellites. The stacking of COMS onto the rocket was followed by installation of the barrel-like payload adapter, Arabsat 5A and the nose cone shroud last week.

Now almost ready to fly, the rocket traveled along rail tracks from the assembly site to the ELA-3 launch pad on Tuesday morning to start the countdown.

Both payloads are headed for geostationary orbits 22,300 miles above the equator. The Arabsat 5A is destined for a parking slot at 30.5 degrees East and COMS will take up residence at 128.3 degrees East.

Arabsat 5A will serve the Arab world with business services and television signal routing. Built jointly by Astrium and Thales Alenia Space using the Eurostar E3000 model design and a 15-year mission life, the craft is equipped with 26 C-band and 24 Ku-band transponders.

"Arabsat 5A multi-mission satellite will provide additional capacity at 30.5 degrees East for a large range of satellite communications services such as television backhauling and broadcasting, telephony, business communications, Internet trunking and the provision of VSAT and other interactive services, over the whole continent of Africa, Central Asia and Middle East region," said Khalid Balkheyour, Arabsat president and CEO.

The Arab Satellite Communications Organization, based in Riyadh, Saudi Arabia, has a cluster of orbiting satellites to reach millions of homes in over 100 countries across the Middle East, Africa, Europe and Asia, relaying hundreds of television channels and radio stations.

The COMS payload is South Korea's new satellite to serve many roles. It features an experimental Ka-band communications package, a weather observation system and equipment to study ocean color and the marine ecosystem to aid the fishing industry.

Astrium built the satellite for the Korea Aerospace Research Institute. The craft, based on the Eurostar E3000 model, has a 10-year mission life.

Wednesday's 64-minute launch opportunity extends from 2141 to 2245 GMT (5:41 to 6:45 p.m. EDT).

Launch day activities get underway at 1111 GMT (6:11 a.m. EDT), and a check of the Ariane 5's electrical systems is scheduled for approximately 1511 GMT (10:11 a.m. EDT). Fueling of the rocket with its load of super-cold liquid hydrogen and liquid oxygen propellant will begin at about 1651 GMT (12:51 p.m. EDT). The chilldown of the Vulcain main engine is planned for 1821 GMT (2:21 p.m. EDT), followed by a final communications check with the rocket at 2031 GMT (4:31 p.m. EDT).

Computers will begin controlling the final moments of the countdown about seven minutes prior to launch. The synchronized launch sequence governs a fast-paced series of automated events transitioning the rocket and payload to internal power, pressurizing fuel tanks, and transitioning systems to flight mode. When clocks reach zero, the Vulcain main engine will fire, followed seven seconds later by ignition of the two solid rocket boosters and liftoff.

The twin solid-fueled motors burn out and jettison at Plus+2 minutes, 20 seconds and the protective payload fairing will be unlatched and released at Plus+3 minutes, 9 seconds. The Ariane 5's first stage shuts down at Plus+8 minutes, 55 seconds, then separates six seconds later. The upper stage's HM-7B engine will begin the final push toward orbit a few seconds later.

After burning for more than 15 minutes, the cryogenic upper stage engine will cut off at Plus+24 minutes, 40 seconds. Deployment of the 10,900-pound Arabsat 5A is scheduled for Plus+26 minutes, 39 seconds. The payload adapter that support the top satellite and enclosed the lower spacecraft jettisons away at Plus+30 minutes, 11 seconds. The 5,400-pound COMS will be released into space at Plus+32 minutes, 38 seconds to complete the launch sequence.

This will be the 195th flight for the Ariane rocket family, the 51st for the Ariane 5 vehicle and the second this year.