Enhanced version of Atlas 5 rocket debuts successfully
BY JUSTIN RAY
Posted: July 17, 2003
The largest and most powerful Atlas rocket in history rushed off its Cape Canaveral pad on a river of golden flame Thursday evening to expand Lockheed Martin's launcher family.
"It is exciting that it puts the final exclamation point on the Atlas 5 family," said Adrian Laffitte, the Atlas launch director.
Lockheed Martin designers made the Atlas first stage and Centaur upper stage, along with their engines, common across the various Atlas 5 configurations. The differences that give each version uniqueness are the fairing size and the strap-on boosters.
The earlier two Atlas 5 missions were based on the 400-series configuration that is distinguished by the "four" meter nose cone. Thursday's launch introduced the 500-series and its Swiss-made "five" meter payload shroud.
The debut appeared flawless as the rocket delivered its commercial cargo -- the Rainbow 1 direct-to-home TV spacecraft -- into the proper orbit to mark the 66th straight success for the Atlas family since 1993.
Riding on its mobile launching platform, the rocket emerged from its assembly building 10 hours before liftoff time. Rolling on rail tracks, the platform journeyed to the launch pad where the rocket was tested, fueled and prepped for flight.
After a 25-minute delay in the final countdown while troublesome clouds passed and two minor technical glitches were dealt with, managers gave their approval to launch.
At 7:45 p.m. EDT (2345 GMT) the Russian RD-180 first stage main engine surged to life, blasting fire and steam from the pad's exhaust duct as the powerplant roared to full thrust. Moments later, the two Aerojet-built solid rocket boosters mounted to the rocket ignited to propel the one-million-pound Atlas 5 off the planet.
Clearing the launch pad structures in just seven seconds, nearly twice as fast as the less-powerful Atlas 5 version that flew the launcher's first two missions, the rocket headed east over the Atlantic Ocean with the kick of over 31 million horsepower.
Burning over 1,000 pounds of solid propellant per second, the two strap-on boosters were exhausted 90 seconds into flight. But citing the desire for conservatism, mission designers delayed jettisoning of the spent motors for 36 seconds until the Atlas 5 moved into a less dynamic regime of ascent.
"We do several things like that, to fly with very high margins for first-flight situation," explained Jim Sponnick, Lockheed Martin's Atlas program vice president.
The 67-foot long, five-foot diameter composite graphite epoxy boosters weren't designed to survive the high-speed water impact for recovery like the space shuttle SRBs. But despite the incredibly remote odds of success, the team sailed from Port Canaveral on Wednesday.
By nightfall Thursday, only a nose cone from one of the boosters had been found. Search operations were expected to resume in the morning, Lockheed Martin said.
Considered the world's longest single-segment solid boosters, the motors provide the additional thrust needed to increase the Atlas 5's payload-carrying capacity. Depending on a satellite's weight, the strap-on boosters can be added one at a time to incrementally increase the amount of cargo the rocket can carry.
For the Atlas 5's 400-series, up to three solids can be used. The 500-series is capable of flying with five.
Illustrating how substantially the Atlas vehicle has grown over the past four decades, the solid boosters are about the same length of the first Atlas ICBMs.
Made by Contraves Space, the fairing shielded the Rainbow 1 satellite atop the Atlas 5 during ascent through Earth's atmosphere.
This new fairing allows Atlas 5 to accommodate much larger cargos.
For more technical details on the solids and the fairing, see our launch preview story.
Within five minutes of liftoff, the Atlas first stage had completed its job and dropped away from the Centaur upper stage and Rainbow 1 spacecraft.
Centaur made two firings, separated by a long coast, to accelerate Rainbow 1 into the prescribed geosynchronous transfer orbit around Earth.
One-hundred minutes into flight, the 9,542-pound Rainbow was cast free from its launcher for the start of an 18-year life to relay television and entertainment programming.
In the coming days, the Lockheed Martin-built craft will fire its onboard kick engine to reach geostationary orbit 22,300 miles above the equator, headed for a parking slot at 61.5 degrees West longitude.
"We are starting from scratch, I'll grant you that. We don't have 10-20 million customers right now," said Wilt Hildenbrand, Cablevision's executive vice president for engineering and technology.
"On the other hand, we are right in the middle of changing times. The world is going digital. The broadcast stations are going digital. People are upgrading to high-definition TV."
Cablevision hopes its state-of-the-art satellite and advances in technology will give the Rainbow service a competitive edge in attracting consumers. However, specific details such as programming and pricing plans have not been announced.
Meanwhile, the next Atlas launch is tentatively scheduled for November 20 from Vandenberg Air Force Base, California. An Atlas 2AS vehicle will place a classified cargo into orbit for the National Reconnaissance Office.
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