Ariane 5 rocket lofts satellite pair for Americas, Australia
BY JUSTIN RAY
Posted: October 5, 2007
An Ariane 5 rocket blasted away from its jungle launch pad in South America on Friday night, overcoming a technical glitch that stopped an initial countdown with just 10 seconds left on the clock.
The giant booster was aiming for an on-time launch at 2128 GMT (5:28 p.m. EDT) to haul a pair of communications satellites into orbit. But the computer-controlled countdown sequence was halted after a problem was detected at the ELA-3 launch pad.
Engineers scrambled to resolve the problem and reset the countdown. The quick work paid off and a fresh seven-minute count commenced at the Guiana Space Center. The remote launch base is located on the northeastern coast of South America in Kourou, French Guiana.
The hydrogen-fueled main engine rumbled to ignition at 2202 GMT (6:02 p.m. EDT), followed seven seconds later with the blinding flash of the twin solid-fuel rocket motors firing to life for liftoff.
Roaring through a few low clouds, the launcher pitched eastward for its half-hour flight to reach geosynchronous transfer orbit with the Intelsat 11 and Optus D2 satellite payloads stacked aboard.
The solid motors burned out and fell away two-and-a-half-minutes into the ascent, leaving the cryogenic main stage to continue propelling the vehicle for another seven minutes. A storable propellant upper stage then took over to power the two Orbital Science-built satellites to their intended altitude.
Arianespace reported the elliptical injection orbit had a high point of 22,316 miles, a low point of 363 miles and inclination of four degrees to the equator.
The Intelsat 11 spacecraft was deployed first, separating nearly 28 minutes after liftoff. A dual-payload launch structure was jettisoned soon thereafter, enabling Optus D2 to be released 32 minutes into the ascent.
It was the 20th consecutive successful launch for the heavy-duty Ariane 5 rocket fleet.
Intelsat 11 is designed to relay direct-to-home TV broadcasting and data networking services to Latin America when it enters service later this year. The craft is equipped with 16 C- and 18 Ku-band transponders.
Controllers will maneuver the satellite into a circular geostationary orbit 22,300 miles above Earth where it can match the planet's rotation and remain parked at 43 degrees West longitude over the equator.
Intelsat says the new craft, with its 16-year life span, will replace the firm's aging Intelsat 6B and 3R satellites.
In Friday night's post-launch jubilations, Kenneth Lee, the Intelsat vice president of space systems management and planning, thanked Arianespace for the smooth ride given to the Intelsat 11 spacecraft. Ariane rockets have launched 47 satellites for Intelsat since 1983.
"This is the reason that we keep coming back for more," Lee said. "Once again, you have demonstrated flexibility, while meeting all of the things that we need - delivering 100 percent."
The Optus D2 satellite will be used for television and communications services to Australia and New Zealand. It features two dozen Ku-band transponders and a design life exceeding 15 years.
Just like its launch partner, the Optus D2 is destined for geostationary orbit. The satellite is headed for 152 degrees East longitude over the equator to replace the Optus B3 craft launched in 1994.
Orbital Sciences has developed a growing niche for small geostationary communications satellites. Friday's liftoff marked the first time that two such spacecraft had been paired together to launch aboard a single rocket.
"Both Intelsat and Optus are very important and valued customers of Orbital and we are committed to extending our history of carrying out successful missions for them," said Senior Vice President Christopher Richmond, head of Orbital's GEO communications satellite programs.
The Ariane 5 rocket has flown four times this year and Arianespace is planning two more. Next on the schedule is a liftoff November 9 carrying the British Skynet 5B military communications satellite and the Brazilian STAR ONE C1 telecommunications spacecraft.
Arianespace says its healthy order book for upcoming launches includes:
The next commercial Soyuz is scheduled for launch from Baikonur on October 21 carrying replacement satellites for the Globalstar mobile telephone network.