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.

The Atlas 5 rocket blasts off from Complex 41 carrying Rainbow 1. Credit: ILS

Sporting new solid-fueled strap-on boosters for added liftoff power and a bulbous nose cone to house bigger satellite cargos, this latest version in the evolving line of Atlas rockets signaled the final qualification for pieces comprising the next-generation Atlas 5.

"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.

The solid rocket boosters separate from the Atlas 5 after their inaugural flight. Credit: ILS video/Spaceflight Now

"We want to congratulate the Atlas team for sheer perfection one more time," said Mark Albrecht, president of Atlas marketing firm International Launch Services. "It is a really awesome team, a national treasure and capability."

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.

An onboard camera shows one of the spent solid rocket boosters falling away from the Atlas 5. Credit: ILS video/Spaceflight Now

The 8,000-pound boosters tumbled into the Atlantic where the space shuttle solid rocket motor retrieval ship, the Liberty Star, and a crew of 19 were waiting with hopes of recovery. Lockheed Martin, NASA and United Space Alliance organized a deal to dispatch the recovery team to snatch the boosters, or at least the nozzles, for post-flight inspections.

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.

Another onboard camera caught this view of the Atlas 5's nose cone separating from the rocket. Credit: ILS video/Spaceflight Now

After the solids were shed from the Atlas 5 Thursday night, the rocket continued on the sole power of the RD-180 engine for a few more minutes. During that time, the 68-foot long, 17-foot diameter nose cone was jettisoned in two halves.

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.

The Centaur upper stage appears as a bright star as it accelerates away from the Atlas 5 rocket's first stage. Credit: ILS video/Spaceflight Now

Three video cameras mounted to various locations on the rocket beamed back stunning views during launch, but arguably the most remarkable scene was captured from a upward-facing camera on the discarded first stage as the Centaur soared toward the blackness of space on the glowing power of its Pratt & Whitney RL10 cryogenic engine.

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.

An illustration of Rainbow 1 in space. Credit: Lockheed Martin

Built for Cablevision, the satellite is the linchpin in the company's plans to create a new direct-to-home TV service across the United States. The system is supposed to be active by October 1, putting Rainbow in a battle with existing satellite broadcasters DirecTV and EchoStar's DISH Network that already have millions of subscribers.

"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.

Video coverage for subscribers only:
   VIDEO: 5 1/2-MINUTE CLIP OF ATLAS 5 LAUNCHING RAINBOW 1 QT
   VIDEO: LAUNCH REPLAY FROM CAMERA ON VIF ASSEMBLY BUILDING QT
   VIDEO: CLOSE-UP VIEW OF SOLID ROCKET BOOSTER AT IGNITION QT
   VIDEO: REPLAY FROM ATLAS SPACEFLIGHT OPERATIONS CENTER QT

   VIDEO: ATLAS 5 ROLLS OUT OF ASSEMBLY BUILDING THURSDAY QT
   VIDEO: THE ROCKET ARRIVES ON COMPLEX 41 LAUNCH PAD QT
   VIDEO: WATCH ENTIRE 41-MINUTE PRE-LAUNCH NEWS CONFERENCE QT
   VIDEO: VIEWS OF THE AEROJET-MADE SOLID ROCKET BOOSTERS QT
   VIDEO: FOOTAGE OF THE CONTRAVES-BUILT PAYLOAD FAIRING QT
   VIDEO: TECHNICIAN CLIMBS INTO THE FAIRING FOR WORK QT
   VIDEO: ATLAS 5 AND SPACE SHUTTLE PADS FROM ATOP THE VIF QT
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