BY JUSTIN RAY

Follow the countdown and launch of the Lockheed Martin Atlas 5 rocket with the Inmarsat 4-F1 mobile broadband communications satellite. Reload this page for the very latest on the mission.

Video coverage for subscribers only:
VIDEO: ATLAS 5 ROCKET BLASTS OFF WITH INMARSAT 4-F1 QT
VIDEO: WATCH EXTENDED LENGTH LAUNCH MOVIE QT
VIDEO: ONBOARD VIEW OF SOLID ROCKET BOOSTER SEPARATION QT
VIDEO: LAUNCH AS SEEN FROM THE PRESS SITE QT

VIDEO: NARRATED ANIMATION PREVIEW OF THIS LAUNCH QT
VIDEO: OVERVIEW OF INMARSAT AND ITS NEWEST SATELLITE QT
VIDEO: TECHNICAL BRIEFING ON THE INMARSAT 4-F1 SPACECRAFT QT
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SATURDAY, MARCH 12, 2005

Riding the most powerful Atlas rocket in history, the world's heaviest commercial communications satellite is circling the Earth following Friday's fast and fiery blastoff from Cape Canaveral. Read our full story.

FRIDAY, MARCH 11, 2005
2214 GMT (5:14 p.m. EST)

T+plus 32 minutes, 20 seconds. SPACECRAFT SEPARATION! The Inmarsat 4-F1 communications satellite has been released into Earth orbit from the Centaur!

This completes the fifth flight of Lockheed Martin's next-generation Atlas 5 rocket, all of which have been successful. It also extends the string of successful missions by the Atlas family to 76 dating back to 1993.

2211 GMT (5:11 p.m. EST)

T+plus 30 minutes. The Centaur is in its reorientation maneuver to prepare for releasing the payload. The vehicle is over 7,000 miles downrange and traveling at 33,540 feet per second.

2211 GMT (5:11 p.m. EST)

T+plus 29 minutes, 29 seconds. MECO! The Centaur's Pratt & Whitney RL10 engine has shut down to complete its second of two firings to launch Inmarsat 4-F1.

2209 GMT (5:09 p.m. EST)

T+plus 27 minutes, 40 seconds. Lockheed Martin says the rocket is performing normally.

2206 GMT (5:06 p.m. EST)

T+plus 24 minutes, 8 seconds. Engine ignition! Centaur is firing again to ferry Inmarsat 4-F1 from its initial parking orbit around Earth into geosynchronous transfer orbit.

2201 GMT (5:01 p.m. EST)

T+plus 19 minutes. The rocket will coast in this parking orbit for about 10 minutes. The Centaur re-ignites at T+plus 24 minutes, 3 seconds for a five-and-a-half minute burn. Deployment of Inmarsat 4-F1 to complete today's launch is expected at T+plus 32 minutes, 17 seconds.

2159 GMT (4:59 p.m. EST)

T+plus 17 minutes. Lockheed Martin says the Centaur main engine completed its first firing a few minutes ago. The stage will propel the Inmarsat mobile communications satellite into the targeted super-synchronous transfer orbit today.

2154 GMT (4:54 p.m. EST)

T+plus 12 minutes. The video and audio feeds of the launch have gone dark here the press viewing area. We will provide addition information on the progress and results of this launch as possible.

2150 GMT (4:50 p.m. EST)

T+plus 8 minutes. The Pratt & Whitney RL10 engine is burning a mixture of liquid oxygen and liquid hydrogen fuel.

2148 GMT (4:48 p.m. EST)

T+plus 6 minutes, 20 seconds. The upper stage is still firing for this first of two burns in the mission.

2147 GMT (4:47 p.m. EST)

T+plus 5 minutes, 35 seconds. The rocket is 434 miles east of the launch pad as Centaur begins its 10-minute firing to reach Earth orbit.

2146 GMT (4:46 p.m. EST)

T+plus 4 minutes, 57 seconds. The four-meter nose cone encapsulating the Inmarsat 4-F1 spacecraft atop the Atlas 5 rocket has separated.

2146 GMT (4:46 p.m. EST)

T+plus 4 minutes, 49 seconds. Centaur's RL10 main engine has ignited!

2146 GMT (4:46 p.m. EST)

T+plus 4 minutes, 38 seconds. And the spent first stage has separated!

2146 GMT (4:46 p.m. EST)

T+plus 4 minutes, 28 seconds. Main engine cutoff confirmed.

2145 GMT (4:45 p.m. EST)

T+plus 3 minutes, 30 seconds. A good flight so far for the Atlas 5 vehicle.

2144 GMT (4:44 p.m. EST)

T+plus 2 minutes, 45 seconds. The Atlas 5 continues powering to space on the Russian-designed RD-180 first stage main engine.

2144 GMT (4:44 p.m. EST)

T+plus 2 minutes, 12 seconds. The solid rocket boosters have been jettisoned from the Atlas 5. The Aerojet-made boosters, the world's longest single-segment solids, have completed their third launch.

2143 GMT (4:43 p.m. EST)

T+plus 95 seconds. All three solid rocket boosters have burned out of propellant. They will remain attached to the vehicle for a little while longer, with two separating at T+plus 2 minutes, 10 seconds and the third spent casing jettisoning a one-and-a-half later.

2142 GMT (4:42 p.m. EST)

T+plus 25 seconds. Atlas 5 has accomplished its roll and pitch maneuvers to achieve the proper profile for minimizing aerogynamic loads.

2142 GMT (4:42 p.m. EST)

T+plus 10 seconds. With its RD-180 main engine roaring at full throttle and the added kick of three powerful strap-on solid rocket boosters, the Atlas 5 rocket has swiftly ascended from the mobile launching platform at Cape Canaveral's Complex 41.

The main engine will be throttling back to 87 percent and then 60 percent during the climb through Earth's dense lower atmosphere. The Russian-designed engine will return to its maximum power setting after burnout of the solid motors.

2142 GMT (4:42 p.m. EST)

LIFTOFF! Liftoff of the most powerful Atlas rocket in history, launching the world's heaviest commercial communications satellite -- the Inmarsat 4-F1 spacecraft.

2141 GMT (4:41 p.m. EST)

T-minus 20 seconds. "Go Atlas," "Go Centaur," "Go Atlas 5" called by launch team, verifying all systems are ready.

2141 GMT (4:41 p.m. EST)

T-minus 1 minute.

2140 GMT (4:40 p.m. EST)

T-minus 90 seconds. Launch control system is enabled. The Flight Termination System has been armed.

2140 GMT (4:40 p.m. EST)

T-minus 2 minutes. The Atlas first stage and Centaur upper stage are now switching to internal power. Liquid oxygen and liquid hydrogen topping for Centaur will be stopped in 10 seconds.

2139 GMT (4:39 p.m. EST)

T-minus 2 minutes, 40 seconds. The Flight Termination System has switched to internal power.

2139 GMT (4:39 p.m. EST)

T-minus 3 minutes. The Atlas first stage liquid oxygen replenishment is being secured so the tank can be pressurized for flight. Also, the RP-1 tank is being pressurized to flight level.

2138 GMT (4:38 p.m. EST)

T-minus 3 minutes, 30 seconds.

2138 GMT (4:38 p.m. EST)

T-minus 4 minutes and counting. The final phase of this afternoon's countdown has begun for the launch of Lockheed Martin Atlas 5 and the Inmarsat 4-F1 communications satellite! The automatic computer sequencer is in control of all the critical events through liftoff.

2136 GMT (4:36 p.m. EST)

The countdown will be coming out of this hold point in two minutes as Lockheed Martin marches forward to today's Atlas 5 rocket flight.

2135 GMT (4:35 p.m. EST)

Launch director Adrian Laffitte has given his "go" to continue the countdown. The Atlas 5 rocket is clear for blastoff at 4:42 p.m. EST.

2135 GMT (4:35 p.m. EST)

The launch team has being polled by the launch conductor in the Atlas Spaceflight Operations Center. All elements are reporting "go" status.

2133 GMT (4:33 p.m. EST)

The Inmarsat 4-F1 spacecraft payload has switching from ground-fed power to internal batteries for flight.

2120 GMT (4:20 p.m. EST)

In about 15 minutes, the launch team will be polled to verify readiness to resume the countdown for liftoff at 4:42 p.m. EST.

2114 GMT (4:14 p.m. EST)

The solid rocket booster ignition safe and arm switch is being put in the "enable" position.

2113 GMT (4:13 p.m. EST)

T-minus 4 minutes and holding. The countdown has entered this final planned hold. The pause is scheduled to last 25 minutes, giving the launch team a chance to catch up on work and deal with any technical issues. Launch remains slated for 4:42 p.m. EST.

2111 GMT (4:11 p.m. EST)

The first stage liquid oxygen tank has achieved flight level. Also, the fuel-fill sequence for the first stage main engine has completed.

2109 GMT (4:09 p.m. EST)

The launch weather officer just completed his last planned briefing to management before liftoff time. Winds continue to gust between 28 and 30 knots at the pad. The launch constraint is 32 knots, and meteorologists do not expect to violate that rule.

2058 GMT (3:58 p.m. EST)

The rocket's "pogo" suppressor has been charged for flight. This energy absorption device aboard is used to damp out oscillations.

2057 GMT (3:57 p.m. EST)

T-minus 20 minutes and counting. The countdown clocks are heading to the T-minus 4 minute mark where a planned 25-minute hold will begin at 4:13 p.m. EST. Liftoff is still set for 4:42 p.m. EST (2142 GMT).

2048 GMT (3:48 p.m. EST)

The Centaur liquid oxygen and liquid hydrogen tanks are reported at flight level.

2042 GMT (3:42 p.m. EST)

Time to launch is 60 minutes.

2035 GMT (3:35 p.m. EST)

Topping of the first stage liquid oxygen tank is underway.

The rocket is nearly fully fueled for launch. However, the liquid oxygen and liquid hydrogen cryogenics being pumped into the rocket this afternoon are chilled to several hundred degrees below zero and naturally boil away. So the supplies must be replenished through the countdown.

2031 GMT (3:31 p.m. EST)

The liquid hydrogen tank in the Centaur upper stage has just reached 97 percent full. Topping is now beginning.

2031 GMT (3:30 p.m. EST)

Although winds are quite strong today along the Space Coast, conditions are not violating the Atlas 5's high threshold for surface winds. The launch weather officer remains optimistic.

2022 GMT (3:22 p.m. EST)

The flight control final preparations are starting as scheduled.

2020 GMT (3:20 p.m. EST)

The Centaur liquid hydrogen tank has reached the 20 percent level. Meanwhile, the first stage liquid oxygen tank is almost three-quarters full.

2017 GMT (3:17 p.m. EST)

The Centaur engine chilldown has been initiated.

2014 GMT (3:14 p.m. EST)

With the liquid hydrogen chilldown now complete, the super-cold fuel is beginning to fill the Centaur upper stage. The cryogenic propellant will be consumed with liquid oxygen by the stage's Pratt & Whitney-made RL10 engine to propel the Inmarsat 4-F1 spacecraft into the targeted super-synchronous transfer orbit this afternoon.

2012 GMT (3:12 p.m. EST)

Launch is just 90 minutes away. Lockheed Martin is not reporting any technical problems, the weather looks good with crystal clear skies and the countdown is running right on schedule. Liftoff is scheduled for 4:42 p.m. EST.

2011 GMT (3:11 p.m. EST)

First stage liquid oxygen tank is now half full.

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-and-a-half minutes of flight today.

2002 GMT (3:02 p.m. EST)

The Centaur liquid oyxgen tank has reached flight level.

Meanwhile, a layer of ice and frost, which is perfectly normal, is forming on the first stage's bronze skin as the super-cold liquid oxygen continues to flow into the vehicle. That tank is 30 percent full.

1956 GMT (2:56 p.m. EST)

The Centaur liquid oxygen tank has now reached the 95 percent level. Topping is starting.

1955 GMT (2:55 p.m. EST)

Ten percent of the first stage liquid oxygen tank has been filled.

1951 GMT (2:51 p.m. EST)

The chilldown conditioning of liquid hydrogen propellant lines at Complex 41 is now starting to prepare the plumbing for transferring the Minus-423 degree F fuel into the rocket.

1947 GMT (2:47 p.m. EST)

The Centaur liquid oxygen tank is now 60 percent full.

1945 GMT (2:45 p.m. EST)

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 super-cold liquid oxygen into the Atlas 5's first stage. The Atlas liquid oxygen tank is the largest tank to be filled today.

The propellant for the first stage -- the RP-1 kerosene -- was loaded aboard the rocket yesterday.

1942 GMT (2:42 p.m. EST)

Launch of the Atlas rocket carrying the Inmarsat 4-F1 spacecraft is two hours away. Fueling operations have commenced at Cape Canaveral's Complex 41. The Centaur liquid oxygen tank is over one-third full.

1930 GMT (2:30 p.m. EST)

Following the thermal conditioning of the transfer pipes, Centaur liquid oxygen tanking operations have begun at Cape Canaveral's Complex 41.

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 high-energy Centaur will perform two firings today to deliver the Inmarsat spacecraft into a super-synchronous transfer orbit.

1924 GMT (2:24 p.m. EST)

The Centaur liquid oxygen transfer line chilldown is starting in advance of loading the upper stage. This thermal conditioning prepares the plumbing for flowing the cryogenic oxidizer.

1917 GMT (2:17 p.m. EST)

T-minus 120 minutes and counting! The countdown has resumed following a planned 75-minute hold. Complex 41 has been primed and readied for today's launch of the Atlas 5 rocket. Liftoff is scheduled to occur at 4:42 p.m. EST, the opening of a 15-minute launch opportunity. One more planned hold is slated for T-minus 4 minutes and will last 25 minutes in duration.

Activities upcoming include pressurizing the first stage kerosene fuel tank and liquid oxygen chilldown procedures.

1912 GMT (2:12 p.m. EST)

The pre-fueling poll of the launch team concluded with all elements reporting "go" to proceed.

1910 GMT (2:10 p.m. EST)

The launch team is receiving a briefing on procedures from the launch conductor before the countdown resumes from this hold at the T-minus 120 minute mark. Next, the team will be polled to verify readiness for fueling the rocket with cryogenic liquid oxygen and liquid hydrogen.

1852 GMT (1:52 p.m. EST)

Now 50 minutes into this planned 75-minute hold.

1820 GMT (1:20 p.m. EST)

The purpose of today's launch is placing the Inmarsat 4-F1 spacecraft into orbit.

"This is a very exciting moment for Inmarsat. There have been people in the company working on this for the past 7 years," CEO Andrew Sukawaty said. "It is the largest commercial satellite to ever be launched. It is a very sophisticated capability we are about to put into the sky. Basically, it is going to expand our services and extend the life of our service to the end of the next decade."

The craft is the first of Inmarsat's newest generation of satellites that come with the tag line "broadband for a mobile planet." Built in Europe by EADS Astrium, the Inmarsat 4-series spacecraft will provide office-like broadband services such as Internet, email, voice and data-relay using laptop and palm-sized terminals on land, at sea or in the air. What's more, they will continue the existing lower-data-rate services currently offered by Inmarsat.

Inmarsat 4-F1 will cover Europe, Africa, the Middle East and Asia, as well as the Indian Ocean. A sister satellite -- Inmarsat 4-F2 -- is scheduled to launch later this year to serve South America, most of North America, the Atlantic Ocean and part of the Pacific Ocean. A third craft is under construction for back up to the first two. If not needed as a replacement, the F3 craft could be deployed over the Pacific.

1802 GMT (1:02 p.m. EST)

T-minus 120 minutes and holding. The countdown has entered the scheduled one-hour, 15-minute paused. Holds like this one are built into the count to provide margin to recover from work running behind schedule and address technical issues. Clocks are slated to resume at 2:17 p.m. EST.

Read our earlier status center coverage.