The Centaur upper stage launching the Cygnus space freighter Tuesday persevered through a velocity shortfall from the first stage of the Atlas 5 rocket, improvising with a longer firing to reach the correct orbit.

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An Atlas 5 rocket successfully launched another Cygnus cargo freighter for Orbital ATK Tuesday night, fulfilling the booster's role of reestablishing America's resupply link to the International Space Station.

Read our launch story.

Solar array deployment confirmed aboard the Cygnus vessel. The circular array design -- dubbed the Mickey Mouse ears -- debuted on the previous freighter to replace the previous retangular ones. The new structures are lighter and more compacted, yet generate the same amount of power.

Wing No. 2 is fully unfurled.

Wing No. 1 is fully unfurled.

The booms holding the arrays both have unfolded.

Solar array deploy operations have begun.

VIDEO REPLAY of today's Atlas 5 rocket launch with Cygnus.

The next Atlas 5 rocket launch from Cape Canaveral is planned for the early afternoon of May 5 to deploy the fifth MUOS mobile communications satellite for the U.S. Navy.

Disposal of the Centaur upper stage by de-orbiting it is underway. Any pieces that survive will be sunk south of Australia.

“ULA is honored to be a part of the team that delivered more than 7,700 pounds of cargo to the astronauts aboard the ISS and CubeSats to be deployed after Cygnus separates from the ISS,” said Gary Wentz, ULA vice president, Human Launch Services.

“Congratulations to our mission partners at Orbital ATK and NASA on another successful launch that will help advance our scientific knowledge on Earth and in space, and inspire the next generation of space explorers.”

This was the 133rd successful Atlas program launch in a row spanning more than two decades and the 62nd for an Atlas 5.

A nominal orbit has been achieved.

T+plus 22 minutes. SPACECRAFT SEPARATION! The Centaur upper stage has deployed the Orbital ATK's commercial Cygnus resupply ship destined to deliver over 7,000 pounds of cargo to the International Space Station some 80 hours from now.

T+plus 19 minutes, 28 seconds. MECO. Centaur's main engine has shut down following the prime burn today, achieving orbit for Cygnus to intercept the International Space Station on Saturday morning.

T+plus 17 minutes, 15 seconds. Everything looking normal with one minute to go in this burn.

T+plus 15 minutes, 30 seconds. RL10 engine parameters still look good.

T+plus 13 minutes. Centaur remains on course and looking good, burning a blend of liquid hydrogen and liquid oxygen.

T+plus 12 minutes, 15 seconds. About six minutes are left in this burn of Centaur. The vehicle is 200 miles in altitude, speeding along at 11,800 mph.

T+plus 10 minutes. All systems reported stable as the Centaur fires to reach an initial Earth orbit for Cygnus.

T+plus 9 minutes. Centaur performance is reported right on target.

T+plus 7 minutes. The rocket is tracking right down the planned flight path.

T+plus 5 minutes. Centaur engine readings look good as this burn gets underway.

T+plus 4 minutes, 50 seconds. The two halves of the four-meter-diameter Atlas 5 rocket nose cone encapsulating the spacecraft have separated.

T+plus 4 minutes, 37 seconds. Centaur has ignited! The RL10C-1 engine is up and running at full thrust to power the vehicle into orbit.

T+plus 4 minutes, 25 seconds. The Atlas 5's Common Core Booster has been jettisoned, completing the first stage of flight, and the Centaur upper stage's liquid hydrogen and liquid oxygen systems are being readied for engine start.

T+plus 4 minutes, 18 seconds. BECO. Booster Engine Cutoff is confirmed as the RD-180 powerplant on the first stage completes its burn. Standing by to fire the retro thrusters and separate the spent stage.

T+plus 3 minutes, 45 seconds. Atlas now weighs just a quarter of what it did at liftoff.

T+plus 2 minutes, 45 seconds. Reaction control system has been activated.

T+plus 2 minutes, 35 seconds. Atlas continues tracking on course.

T+plus 2 minutes, 30 seconds. Atlas now weighs half of what it did at liftoff.

T+plus 2 minutes, 15 seconds. Vehicle systems looking good.

T+plus 1 minutes, 45 seconds. The RD-180 main engine continues to fire normally, burning a mixture of highly refined kerosene and liquid oxygen.

T+plus 95 seconds. Now passing through the region of maximum aerodynamic pressure on the vehicle as its accelerates through the dense lower atmosphere.

T+plus 85 seconds. All looks good aboard Atlas as it passes Mach 1.

T+plus 60 seconds. Cygnus is racing to the International Space Station for rendezvous on Saturday morning to deliver over 7,000 pounds of goods, food and new science experiments.

T+plus 40 seconds. The Atlas 5 has maneuvered on course to take aim on the International Space Station, heading northeast from Cape Canaveral toward an orbit of 51.6 degrees.

T+plus 15 seconds. The Atlas 5 rocket has cleared the tower on 860,000 pounds of thrust from the RD-180 main engine. Pitch, yaw and roll maneuvers are underway to put the rocket on the proper heading.

LIFTOFF! Liftoff of the Atlas 5 and Cygnus -- launching provisions and supplies to the laboratories and crew at the International Space Station!

T-minus 20 seconds. "Go Atlas" and "Go Centaur" and "Go OA-6" was just called by launch team during a final status check.

T-minus 40 seconds. Centaur's liquid oxygen and liquid hydrogen tanks are stable at flight pressures.

T-minus 1 minute. Now 60 seconds from liftoff. At the time of launch, the space station will be flying 251 miles over the Bahamas, just off the coast of Florida.

T-minus 90 seconds. The safety system has been armed.

T-minus 1 minute, 45 seconds. Liquid oxygen and liquid hydrogen propellant topping to the Centaur upper stage is being secured.

T-minus 1 minute, 55 seconds. The launch sequencer has been commanded to start.

T-minus 2 minutes. The Atlas first stage and Centaur upper stage are now switching from ground power to internal batteries.

T-minus 2 minutes, 30 seconds. The first stage RP-1 kerosene fuel tank and the liquid oxygen have stepped up to proper flight pressure levels.

T-minus 3 minutes. The Atlas first stage liquid oxygen replenishment is being secured so the tank can be pressurized for launch.

T-minus 3 minutes, 50 seconds. The ground pyrotechnics have been enabled.

T-minus 4 minutes and counting. Clocks have resumed for the final minutes of today's countdown to launch the Atlas 5 rocket carrying Cygnus resupply ship for the space station.

Countdown clocks will resume in one minute.

The ULA launch director has given the permission to fly today.

Polling of the team by Atlas launch conductor has occurred. All systems are reported "go" to continue with the countdown for liftoff at 11:05:52 p.m. EDT.

Standing by for the launch team readiness polls.

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Cygnus is on internal power and go for launch.

No problems being reported by the launch team. Countdown continues to sit in the hold period at T-minus 4 minutes, waiting for the launch window to open at 11:05 p.m. EDT.

Here's a look at some stats about today's mission. This will be:

• The 644th launch for Atlas program since 1957
• The 349th Atlas launch from Cape Canaveral
• The 233rd mission of a Centaur upper stage
• The 210th use of Centaur by an Atlas rocket
• The 467th production RL10 engine to be launched
• The 11st RL10C-1 engine launched
• The 68th flight of the RD-180 main engine
• The 62nd launch of an Atlas 5 since 2002
• The 14th commercial mission for an Atlas 5
• The 93rd Evolved Expendable Launch Vehicle flight
• The 106th United Launch Alliance flight overall
• The 54th Atlas 5 under United Launch Alliance
• The 42nd 400-series flight of the Atlas 5
• The 32nd Atlas 5 to fly in the 401 configuration
• The 6th Cygnus spacecraft to launch
• The 5th Orbital ATK Commercial Resupply Services mission
• The 12th Combined launch under CRS program for NASA
• The 2nd Cygnus on an Atlas rocket
• The 2nd Atlas rocket for International Space Station
• The 2nd Enhanced Cygnus

The Cygnus freighter nestled inside the nose of the Atlas 5 rocket is switching to internal power for launch.

Weather remains GO for liftoff based on the current conditions and expected to stay favorable for launch today. The odds are 100 percent.

Thirty minutes from liftoff of the Atlas 5 rocket on its second mission for the International Space Station.

T-minus 4 minutes and holding. The countdown has entered the planned 30-minute hold to give the launch team a chance to review all systems and assess the weather before pressing ahead with liftoff.

T-minus 5 minutes. Standing by to go into the final built-in hold.

Now 45 minutes till launch. Rumbling away from the planet on nearly a million pounds of thrust, the Atlas 5 rocket will be flying in a basic, two-stage configuration without any added strap-on solid motors. The vehicle sports an aluminum, 14-foot-diameter nose cone that encapsulates the Cygnus spacecraft during the atmospheric ascent before being shed.

With the liftoff thrust not considerably more than the rocket's weight, this Atlas will display a slow and majestic rise trailing only a flickering golden flame from its RD-180 main engine.

Once above the launch pad, the rocket sets sail for the trek over the Atlantic Ocean, constantly gaining speed as its double-nozzle engine gulps 25,000 gallons of kerosene fuel and 50,000 gallons of superchilled liquid oxygen in just four-and-a-quarter minutes.

The bronze first stage, its propellants depleted and job now completed, then jettisons with the help of tiny thrusters. Some 106.5 feet long and 12.5 feet around, the stage is discarded to fall back into the open sea.

The cryogenic Centaur upper stage ignites moments after shedding the lower booster, lighting the RL10 engine to continue clawing toward orbit.

Covered with insulating foam, this stage stretches 41.5 feet in length and 10 feet in diameter. Centaur must perform a lengthy burn to loft Cygnus into the proper orbit around the planet.

Today marks the 62nd flight for Atlas 5, born of the Air Force's competition to develop next-generation Evolved Expendable Launch Vehicles. In its previous 61 missions since debuting in August 2002, the Atlas 5 has flown 24 flights dedicated to the Defense Department, 13 commercial missions, 12 for NASA, 12 with spy satellites for the National Reconnaissance Office.

Now 60 minutes from liftoff. Fueling of the Atlas rocket with cryogenic liquid oxygen and liquid hydrogen is complete as the countdown continues as planned for a liftoff at 11:05:52 p.m. EDT.

PREVIEW: A hundred days after the last U.S. commercial resupply of the International Space Station by a Cygnus cargo ship launched atop an Atlas 5 rocket, the booster and freighter duo will do it again tonight.

Read our preview story.

The liquid hydrogen tank in the Centaur upper stage just reached the 96 percent level. Topping is now beginning.

Fast-filling of the first stage liquid oxygen tank has been completed. Topping mode is now underway.

Centaur's liquid hydrogen tank is 30 percent full. The cryogenic propellant will be consumed with liquid oxygen by the stage's Aerojet Rocketdyne-made RL10C engine.

The first stage liquid oxygen has reached the 70 percent level.

Chilldown of the liquid hydrogen system has been accomplished. The launch team has received the "go" to begin filling the Centaur upper stage with the supercold fuel.

Half of the Atlas liquid oxygen tank has been filled so far.

First stage liquid oxygen tank is 30 percent full thus far. Chilled to Minus-298 degrees F, the liquid oxygen will be used with RP-1 kerosene by the RD-180 main engine on the first stage during the initial four minutes of flight today. The 25,000 gallons of RP-1 were loaded into the rocket Monday.

Upper stage liquid oxygen has reached flight level.

The Centaur liquid oxygen tank reached the 96 percent level. The topping off process is starting now.

The first stage liquid oxygen flow rate is switching from slow-fill to fast-fill mode.

The chilldown conditioning of liquid hydrogen propellant lines at Complex 41 is starting to prepare the plumbing for transferring the Minus-423 degree F fuel into the rocket. The Centaur holds about 12,700 gallons of the cryogenic propellant.

Three-quarters of the Centaur liquid oxygen tank has been filled so far.

The chilldown conditioning of the systems for the first stage liquid oxygen tank have been completed. And a "go" has been given to begin pumping supercold liquid oxygen into the Atlas 5's first stage.

The Common Core Booster stage's liquid oxygen tank is the largest tank to be filled today. It holds 50,000 gallons of cryogenic oxidizer for the RD-180 main engine.

The Centaur liquid oxygen tank has reached the 20 percent mark.

Learn more about the process United Launch Alliance uses to fuel Atlas 5 rockets.

Filling of the Centaur upper stage with about 4,150 gallons of liquid oxygen has begun at Cape Canaveral's Complex 41 following the thermal conditioning of the transfer pipes.

The liquid oxygen -- chilled to Minus-298 degrees F -- will be consumed during the launch by the Centaur's single RL10 engine along with liquid hydrogen to be pumped into the stage a little later in the countdown. The Centaur will provide the thrust to put Cygnus into orbit.

The Centaur liquid oxygen pad storage area has been prepped. The next step is conditioning the transfer lines, which is now beginning to prepare the plumbing for flowing the cryogenic oxidizer.

T-minus 2 hours and counting! The launch countdown is continuing on schedule for today's flight of the Atlas 5 rocket to deploy the Cygnus cargo freighter for Orbital ATK.

Clocks have one more built-in hold planned at T-minus 4 minutes. During that pause the final "go" for launch will be given. All remains targeted for liftoff at 11:05:52 p.m. EDT from Cape Canaveral's Complex 41.

The available launch opportunities today:

* 11:05:52 p.m. EDT
* 11:13:22 p.m. EDT
* 11:20:52 p.m. EDT (in-plane)
* 11:25:14 p.m. EDT
* 11:32:44 p.m. EDT

In the next couple of minutes, chilldown thermal conditioning of the mobile launch platform upon which the rocket stands will begin. This is meant to ease the shock on equipment when supercold cryogenic propellants start flowing into the rocket.

After briefing his team on procedures before entering into the final two hours of the countdown, the launch conductor at the Atlas Spaceflight Operations Center just held a pre-fueling readiness poll.

All console operators reported a "ready" status.

The ULA launch director also voiced approval for proceeding with the countdown.

Loading of cryogenic liquid oxygen and liquid hydrogen into the Atlas 5 rocket will be getting underway a short time from now.

Man stations for cryogenic tanking. That's the word to the launch team.

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T-minus 2 hours and holding. The countdown has just entered the first of two planned holds over the course of the day that will lead to the 11:05:52 p.m. EDT launch of the Atlas rocket. The holds give the team some margin in the countdown timeline to deal with technical issues or any work that is running behind. The final hold is scheduled to occur at T-minus 4 minutes.

Crews are departing the launch pad following completion of all hands-on work today. Fueling operations for the launch vehicle will be starting in about an hour.

The weather outlook at Cape Canaveral continues to be excellent tonight, the launch meteorologist reports in his pre-fueling briefing.

Skies are mostly clear, the radar is free of showers and winds are light. There are no weather violations expected this evening.

The launch time outlook predicts a scattered clouds at 4,000 feet, good visibility, southeasterly winds of 8 gusting to 12 knots and a temperature of 64 degrees F.

Still counting down on schedule with no issues for launch at 11:05 p.m. EDT (0305 GMT).

Tonight's launch of the Cygnus freighter for space station is carrying 7,485 pounds of cargo.

Tonight marks Orbital ATK’s sixth Cygnus built, the fifth operational mission to launch and the second in three months

The early portion of the countdown has been going very well today. There's no issues being reported in the count and activities are on schedule for liftoff at 11:05 p.m. EDT (0305 GMT).

Today marks the 62nd flight of the Atlas 5. It has flown 24 Department of Defense flights, 13 commercial missions, 12 for NASA and 12 for the National Reconnaissance Office.

If you are need tips on picking a good viewing spot, check out this authoritative guide on where to go.

In today's first weather briefing to mission managers, the odds for favorable conditions during the launch window stand at "greater than" 90 percent. High pressure is building in, bringing good weather for launch tonight.

The launch time outlook predicts just some scattered clouds at 4,000 feet, good visibility, southeasterly winds of 10 gusting to 14 knots and a temperature of 64 degrees F.

The countdown just began for the United Launch Alliance Atlas 5 rocket and the commercial Orbital ATK Cygnus cargo freighter to intercept the International Space Station from Cape Canaveral.

Clocks are picking up the seven-hour sequence of work that will prepare the booster, payload and ground systems for blastoff.

The available launch opportunities today:

* 11:05:52 p.m. EDT
* 11:13:22 p.m. EDT
* 11:20:52 p.m. EDT (in-plane)
* 11:25:14 p.m. EDT
* 11:32:44 p.m. EDT

There is a 90 percent chance of allowable weather. Cumulus clouds are the worry tonight.

The launch team will soon begin powering up the rocket to commence standard pre-flight tests. Over the subsequent few hours, final preps for the Centaur's liquid oxygen and liquid hydrogen systems will be performed, along with a test of the rocket's guidance system and the first stage propulsion and hydraulic preps, internal battery checks and testing of the GPS metric tracking system used to follow the rocket as it flies downrange, plus a test of the S-band telemetry relay system.

A planned 30-minute hold begins when the count reaches T-minus 2 hours. Near the end of the hold, the team will be polled to verify all is in readiness to start fueling the rocket for launch.

Supercold liquid oxygen begins flowing into the Centaur upper stage, followed by the first stage filling. Liquid hydrogen fuel loading for Centaur will be completed a short time later.

A final 30-minute hold is scheduled at the T-minus 4 minute mark. That pause will give everyone a chance to finish any late work and assess the status of the rocket, payload, Range and weather before proceeding into the last moments of the countdown.

Taking aim on the International Space Station with another cargo-laden resupply ship, a United Launch Alliance Atlas 5 rocket moved from the assembly building to the pad this morning for Tuesday night's liftoff.

Launch is targeted for 11:05:51 p.m. EDT at the opening of a 30-minute window, leading to rendezvous with the station early Saturday.

The Atlas 5 is topped by Orbital ATK's commercial Cygnus supply freighter, which is filled with over 7,000 pounds of provisions, equipment and science gear for the station and its residents.

The United Launch Alliance booster was wheeled out aboard a mobile platform, emerging from the Cape Canaveral facility where the rocket's two stages and the payload were integrated over the past month.

The slow drive from the 30-story Vertical Integration Facility to the launch pad, which began at 10 a.m., used a pair of specially-made “trackmobiles” to carry the rocket's 1.4-million pound mobile launching platform along rail tracks for the 1,800-foot trip.

The 194-foot-tall booster will launch the Cygnus craft into a 143-mile orbit to begin its chase of the station. Deployment of the spacecraft from the rocket occurs 21 minutes after liftoff.

"It is more excitement than nervousness. I always think of it like a couple days before the big exam or the big game or the big performance that you're doing. You just have to believe you've done the right work and then get your head into the next phase," said Dan Tani, former space shuttle and station astronaut and now the senior director for mission and cargo operations at Orbital ATK.

"We need to get our head in the game in terms of operating this vehicle. My mission operations team is going through many rehearsals and they are ready to take command of this thing once it separates from the launch vehicle."

The rocket is flying the 401 vehicle configuration. The version features two stages and a four-meter-diameter nose cone. It is powered off the launch pad by an RD AMROSS RD-180 main engine. The Centaur upper stage is equipped with an Aerojet Rocketdyne RL10C-1.

Countdown clocks begin ticking seven hours before launch, leading to activation of the rocket, final testing and system preps.

There is a 90 percent chance of acceptable launch weather.

"On launch day, high pressure pushes east of the peninsula with on-shore winds during the day and becoming from the southeast during the window with gusts in the low to mid-teens. With the on-shore flow, there is a small coastal shower threat. No thunderstorms are expected. The primary concern for launch, although slight, is cumulus clouds," the launch weather team says.

NOW: Rollout of the Atlas 5 rocket is underway for Tuesday's 11:05 p.m. EDT launch of the International Space Station cargo vessel.

The weather forecast has improved to 90 percent GO.

PREVIEW: A hundred days after the last U.S. commercial resupply of the International Space Station by a Cygnus cargo ship launched atop an Atlas 5 rocket, the booster and freighter duo will do it again Tuesday.

Read our full story.

The official weather forecast is 80 percent GO for Tuesday night's Atlas 5 launch of Cygnus. The Launch Readiness Review was conducted today and granted approval to press ahead with Monday's rollout.

TIMELINE: Follow the Atlas 5 rocket’s ascent into orbit from Cape Canaveral’s Complex 41 launch pad with the Orbital ATK Cygnus resupply ship for the International Space Station. Launch is scheduled for Tuesday at 11:05 p.m. EDT (0305 GMT).

See our full timeline.

METEOR: Peering down at the Earth’s atmosphere from a research window aboard the International Space Station, a new science instrument launching Tuesday will compose unprecedented characterizations of the chemical makeup of shooting stars.

Read our full story.

SAFFIRE: Working via remote control this spring, scientists will spark a fire aboard the unmanned Cygnus cargo ship that launches next Tuesday to study how the deliberate flames spread in weightlessness.

Read our full story.