BY JUSTIN RAY

Follow the countdown and launch of the Lockheed Martin Atlas 3B rocket with the U.S. Navy's UHF F11 communications satellite. Reload this page for the very latest on the mission.

1840 GMT (1:40 p.m. EST)

As scheduled at this point in the countdown, the launch team is powering up the Atlas 3B rocket at pad 36B. A short time ago, propulsion system preparations for the Centaur upper stage began.

Looking ahead at the highlights of activities planned through liftoff: Atlas propulsion and hydraulic systems preps, launch pad umbilical tower and mobile service structure preps, performing the flight control operational test, the internal power test of Atlas-Centaur, performing a navigation test of rocket's guidance computer, starting Centaur helium purges and starting liquid hydrogen and liquid oxygen system final preps.

The Integrated Launch Operations -- the final portion of the countdown in which all members of the launch team participate -- will start at 6:15 p.m. EST (2315 GMT). Retraction of the mobile service tower from around the rocket is slated for 6:30 p.m. EST.

Countdown clocks will enter a planned 30-minute hold at the T-minus 105 minute mark starting at 7:00 p.m. During this time the launch team will have a chance to catch up on any work that could be running behind schedule.

Fueling operations will commence at 7:44 p.m. with super-cold liquid oxygen flowing into the Centaur upper stage. Loading of liquid oxygen into the Atlas booster stage should start at 8:05 p.m. The final segment of fueling will begin at 8:21 p.m. when liquid hydrogen is pumped into the Centaur. The Atlas stage was previously fueled with its supply of RP-1 kerosene propellant.

A final planned hold is scheduled at T-minus 5 minutes for 15 minutes in duration starting at 9:10 p.m. If there are no problems standing in the way of liftoff, the countdown will resume at 9:25 p.m. for an on-time launch.

Tonight's available window to get the rocket airborne extends two hours from 9:30 to 11:30 p.m. EST (0230-0430 GMT).

1805 GMT (1:05 p.m. EST)

The second countdown is underway at Cape Canaveral for the launch of Lockheed Martin's Atlas 3B rocket and the U.S. Navy's UHF F11 communications satellite. Liftoff is set to occur at 9:30 p.m. EST (0230 GMT) tonight.

Air Force meteorologists have issued a new weather forecast today, which calls for a 40 percent chance of gusty winds violating the launch weather rules. See the full forecast here.

1525 GMT (10:25 a.m. EST)

Repair efforts at launch pad 36B were successfully completed last night, clearing the way for today's countdown and flight of the Lockheed Martin Atlas 3B rocket. Countdown clocks are slated to begin ticking at 12:40 p.m. EST.

Liftoff is scheduled for 9:30 p.m. EST tonight. However, officials have nixed the idea of extending the available launch window an extra hour. Therefore, the window is now two hours in length, running until 11:30 p.m. EST.

TUESDAY, DECEMBER 16, 2003
2235 GMT (5:35 p.m. EST)

Technicians will replace faulty seals in the liquid oxygen fill and drain valve feeding the Atlas 3B rocket's first stage, correcting a problem that caused Monday's initial launch attempt to be scrubbed, officials decided at an afternoon meeting today.

During Monday's countdown, the valve seals allowed cryogenic liquid oxygen to over-chill a bolt-cutter device that is used to separate the ground equipment from the rocket at liftoff. The concern was the system would not operate correctly at the lower-than-expected temperature, Lockheed Martin officials said.

Once the seals are changed out later tonight and testing is performed, the Lockheed Martin-built rocket and its U.S. Navy communications satellite will be ready for a second launch attempt on Wednesday evening.

Liftoff from pad 36B at Cape Canaveral Air Force Station is targeted for 9:30 p.m. EST (0230 GMT).

To maximize the launch opportunity, officials plan to lengthen the evening's available window from two hours to three. That means the rocket will have until 12:30 a.m. EST (0530 GMT) to lift off.

Weather forecasters are predicting a 40 percent chance that strong winds will prohibit the launch. A frontal system is expected to pass through the Central Florida area well before liftoff time, but gusty winds are likely through the evening.

Meteorologists say the winds should ease as the night goes on, meaning the extra hour added to the launch window could be key to ensuring the Atlas has ample time to fly Wednesday.

Winds cannot be greater than 25 knots (from the northerly direction expected Wednesday) for the launch to occur. Weather officer Johnny Weems is calling for winds of 15 gusting to 21 knots at launch time.

1800 GMT (1:00 p.m. EST)

The latest weather forecast for Wednesday, and a look to Thursday and Friday if the launch slips further, is available here.

Lockheed Martin engineers are assessing the plan to resolve the hardware problem that scrubbed Monday's night countdown. Officials continue to target a Wednesday evening launch attempt.

TUESDAY, DECEMBER 16, 2003
0420 GMT (12:20 a.m. EST)

Launch weather officer Johnny Weems is predicting a 60 percent chance of acceptable conditions for liftoff of the Atlas 3B rocket on Wednesday night. Meteorologists are worried that northwest winds, gusting above 25 knots, will violate the launch time wind limit.

0330 GMT (11:30 p.m. EST Mon.)

Monday night's shot at launching a Lockheed Martin Atlas 3B rocket carrying the final in a series of U.S. Navy communications satellites was postponed after a device that helps release the booster from its launch pad was subjected to colder-than-allowable temperatures, officials said. Liftoff is tentatively rescheduled for Wednesday night. Read our full scrub story.

0325 GMT (11:25 p.m. EST Mon.)

NEW DATE! Lockheed Martin has rescheduled the launch for Wednesday night at 9:30 p.m. EST.

0256 GMT (9:56 p.m. EST Mon.)

A little more detail is confirmed from Lockheed Martin on this bolt-cutter. It is used as part of the separation system to release the rocket from the launch pad at liftoff. The device supports the Atlas first stage liquid oxygen fill and drain valve.

The mobile service tower has been rolled back to the rocket, although it is not yet fully enclosing the vehicle. The draining of cryogenic propellants continues, as well as other post-scrub chores.

We will pause our coverage at this point. Watch this page for the announcement of a new launch date. That news could be made available later tonight or in the morning, according to Lockheed Martin.

0245 GMT (9:45 p.m. EST Mon.)

Still no official word on when the launch will be rescheduled. If liftoff is reset for Tuesday night, the launch window extends from 9:34 to 11:34 p.m. EST. The two-hour window on Wednesday opens at 9:30 p.m. EST.

0235 GMT (9:35 p.m. EST Mon.)

Here is how the scrub decision was announced:

Anomaly Resolution Team: "The Anomaly Team has researched the bolt-cutter anomaly...The temperatures that it had dropped to is below the qualification temperature. At this time, we are recommending we stand down for tonight's operation."

Launch conductor: "Roger, concur."

Launch conductor: "Launch director, LC."

Launch director: "Go ahead."

Launch conductor: "Recommend we scrub tonight's operation."

Launch director: "Copy and concur, and let's make sure we have a spare ready to go to replace the bolt-cutter."

0227 GMT (9:27 p.m. EST Mon.)

Launch of the Lockheed Martin Atlas 3B rocket with a U.S. Navy communications satellite aboard has been scrubbed for tonight after a bolt-cutter on the first stage liquid oxygen fill and drain valve became too cold during the countdown. The temperature at which the device is qualified for use was violated, prompting officials to scrub the launch. When the next launch attempt will occur has not yet been formalized.

0225 GMT (9:25 p.m. EST Mon.)

The launch team is now preparing to drain the cryogenic liquid oxygen and liquid hydrogen propellants from the Atlas 3B rocket as part of standard post-scrub activities. Again, launch has been postponed for the night. A new launch date has not been announced.

0223 GMT (9:23 p.m. EST Mon.)

SCRUB! Tonight's launch attempt is being scrubbed after the Anomaly Resolution Team's research found that the Atlas stage liquid oxygen fill and drain valve bolt-cutter temperature dipped below the unit's qualified value. As a result, liftoff will not occur tonight. Launch director Adrian Laffitte has instructed the team to get a spare bolt-cutter ready.

0223 GMT (9:23 p.m. EST Mon.)

The Centaur hydrogen tank is now 97 percent, heading to flight level.

0222 GMT (9:22 p.m. EST Mon.)

Anomaly Resolution Team says its sees a warming of the Atlas stage liquid oxygen fill and drain valve bolt-cutter temperature. So the approval has been given to start topping the oxygen tank to flight level.

Meanwhile, an inhibited self test of the rocket's Flight Termination System is starting. The FTS would be used to destroy the vehicle in the event of a malfunction during launch.

0219 GMT (9:19 p.m. EST Mon.)

The Centaur liquid hydrogen tank has reached the 80 percent level.

0215 GMT (9:15 p.m. EST Mon.)

The Atlas liquid oxygen tank has reached the 98 percent level where it is being maintained. Topping to 100 percent will be completed shortly.

0210 GMT (9:10 p.m. EST Mon.)

All weather rules remain "go". It is a beautiful evening at Cape Canaveral.

The Atlas oxygen tank is now 90 percent full; the Centaur hydrogen tank has reached 30 percent; the Centaur oxygen tank is at flight level.

0208 GMT (9:08 p.m. EST Mon.)

Launch of the Atlas 3B rocket is now 60 minutes away. The launch team is active with work to load the Atlas liquid oxygen and Centaur liquid hydrogen tanks. The Centaur oxygen tank was filled earlier in the count.

0204 GMT (9:04 p.m. EST Mon.)

The Centaur engine gaseous helium chilldown has started as the countdown heads to the new launch time of 10:08 p.m. EST tonight from Cape Canaveral Air Force Station, Florida.

0202 GMT (9:02 p.m. EST Mon.)

The liquid hydrogen chilldown is now complete and the "go" has been given to load the super-chilled fuel into 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 Navy's UHF F11 spacecraft into the targeted geosynchronous transfer orbit tonight.

0200 GMT (9:00 p.m. EST Mon.)

The Atlas liquid oxygen tank is now 40 percent full. The rocket's first stage is icing over as the super-cold liquid oxygen continues to flow into the vehicle.

Anomaly Resolution Team is discussing a redline limit that has been tripped. The Atlas stage liquid oxygen fill and drain valve bolt-cutter temperature has gone below the threshold limit and is dropping, the team says.

0157 GMT (8:57 p.m. EST Mon.)

The Atlas liquid oxygen tank is now at the 20 percent level.

0154 GMT (8:54 p.m. EST Mon.)

The Centaur liquid oxygen tank, which was loaded a little while ago, is now being topped to flight level.

0153 GMT (8:53 p.m. EST Mon.)

T-minus 60 minutes and counting. Clocks continue to tick down to the revised launch time of 10:08 p.m. EST tonight. There will be a planned 15-minute hold at the T-minus 5 minute point.

0148 GMT (8:48 p.m. EST Mon.)

The Anomaly Resolution Team says that the second pneumatic charging problem will not impact the countdown and the recommendation is to proceed.

0145 GMT (8:45 p.m. EST Mon.)

The "go" has been given to commence loading of the Atlas first stage liquid oxygen tank.

0143 GMT (8:43 p.m. EST Mon.)

T-minus 70 minutes and counting! The countdown is back underway at Cape Canaveral for tonight's launch of the Atlas 3B rocket carrying a Navy communications satellite. The launch has been delayed 30 minutes to 10:08 p.m. EST after technicians were sent into the pad to work on a valve.

With the count progressing again, the next major event will be loading liquid oxygen into the first stage.

0141 GMT (8:41 p.m. EST Mon.)

NEW LAUNCH TIME SET. The countdown will resume at 8:43 p.m. EST from the T-minus 70 minute mark. Liftoff is now targeted for 10:08 p.m. EST, a half-hour later than planned.

0140 GMT (8:40 p.m. EST Mon.)

The chilldown conditioning of liquid hydrogen propellant lines at pad 36B is now starting to prepare the plumbing for transferring the Minus-423 degree F fuel into the rocket.

0138 GMT (8:38 p.m. EST Mon.)

Now one hour away from the originally-scheduled launch time. However, liftoff has been pushed back while technicians went to the launch pad to fix a valve issue.

That crew sent to the pad has completed its work and has departed already. The launch is now getting set to resume hazardous countdown activities that were suspected while the personnel were at the pad.

0128 GMT (8:28 p.m. EST Mon.)

Countdown clocks have been paused at the T-minus 70 minute mark for some 15 minutes now. This hold will delay liftoff past the 9:38 p.m. EST target. But there is a full two-hour launch window available tonight to get the rocket airborne.

0121 GMT (8:21 p.m. EST Mon.)

The Anomaly Resolution Team is also assessing a second charging problem with the Atlas pneumatic system.

At this point, the launch team is safing systems for the crew's entry into the pad.

0119 GMT (8:19 p.m. EST Mon.)

There is no word on how long this unexpected delay in the countdown will last. However, tonight's launch window extends for two hours, giving the team a good deal of margin to resolve this valve problem. The window runs from 9:38 to 11:38 p.m. EST.

0114 GMT (8:14 p.m. EST Mon.)

A five-person crew is assembling to go into pad 36B to work on a manual isolation valve that appears to be closed when it should be open.

Meanwhile, the Centaur liquid oxygen tank has reached 95 percent full level where it is being secured.

0113 GMT (8:13 p.m. EST Mon.)

T-minus 70 minutes and holding! The countdown has gone into an unplanned hold while efforts are performed to fix a valve problem at the launch pad.

0110 GMT (8:10 p.m. EST Mon.)

The Centaur liquid oxygen tank is now at the 80 percent point.

0109 GMT (8:09 p.m. EST Mon.)

The Anomaly Resolution Team says a manually-controlled isolation valve at the pad is preventing the Atlas pneumatic system from being charged. The valve apparently is closed. So a crew will have to be sent back into the pad to open the valve. Liquid hydrogen fueling preps will be delayed until after the crew completes its work and clears the pad.

0105 GMT (8:05 p.m. EST Mon.)

The launch team reports that the Centaur liquid oxygen tank is now half-full.

Members are also looking at an issue with the pneumatic system on Atlas.

0100 GMT (8:00 p.m. EST Mon.)

The Centaur liquid oxygen tank has reached the 20 percent mark in these early minutes of fueling activities tonight.

0058 GMT (7:58 p.m. EST Mon.)

The final alignment of the Atlas rocket's inertial navigation guidance computer has been completed. The flight control system final preps have begun.

0051 GMT (7:51 p.m. EST Mon.)

The chilldown conditioning of the liquid oxygen transfer lines at pad 36B is complete. The "go" has now been given to start filling the Centaur upper stage with its its supply of super-cold cryogenic oxidizer.

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.

0039 GMT (7:39 p.m. EST Mon.)

Safety officials have confirmed that the danger area around the launch pad is cleared of all personnel. This allows the "chilldown" procedure to start for thermal conditioning of the liquid oxygen fuel lines at pad 36B in advance of loading the Centaur upper stage.

0038 GMT (7:38 p.m. EST Mon.)

T-minus 105 minutes and counting. The countdown has resumed following the planned half-hour hold.

The countdown will continue to T-minus 5 minutes where a planned 15-minute built-in hold is scheduled. Launch of the Atlas 3B rocket with the U.S. Navy's UHF F11 communications satellite is still targeted for two hours from now at 9:38 p.m. EST.

0035 GMT (7:35 p.m. EST Mon.)

At launch pad 36B, workers have completed securing work following mobile service tower rollback. Launch conductor Ed Christiansen has instructed them to clear the area.

0034 GMT (7:34 p.m. EST Mon.)

The launch team has verified its readiness for the upcoming fueling operations as cryogenic liquid oxygen and liquid hydrogen propellants are pumped into the Atlas and Centaur stages. No problems were reported during the poll by launch conductor Ed Christiansen. Launch director Adrian Laffitte then gave a "ready" status.

0028 GMT (7:28 p.m. EST Mon.)

Ten minutes are remaining in this hold at T-minus 105 minutes. In about five minutes, a readiness check of the launch team will be performed by Lockheed Martin launch conductor Ed Christiansen in preparation for fueling the rocket.

0018 GMT (7:18 p.m. EST Mon.)

Now one-third of the way through this planned hold in the countdown. With the mobile service tower rolled back, the final securing of the launch complex is being performed before workers clear the pad. The hazardous operation of loading cryogenic propellants into the vehicle will begin after the countdown resumes.

0008 GMT (7:08 p.m. EST Mon.)

T-minus 105 minutes and holding. The countdown has entered a planned 30-minute built-in hold for tonight's launch of the Atlas 3B rocket from Cape Canaveral Air Force Station, Florida.

The count has 45 minutes of holds scheduled over the course the evening that will lead to liftoff at 9:38 p.m. EST (0238 GMT). A second and final hold is planned at T-minus 5 minutes for 15 minutes. The holds are designed to give the launch team a window of time to work any problems that could arise.

At this point, Lockheed Martin is not reporting any issues as launch preparations continue on schedule.

0006 GMT (7:06 p.m. EST Mon.)

The Air Force has announced there is one Collision Avoidance period, or COLA, that will prohibit liftoff for a few minutes during tonight's launch window. The COLA extends from 11:23:00 to 11:27:41 p.m. EST.

COLA cutouts occur to ensure the rocket isn't launched on a course that would take it too close to an object already orbiting in space.

0003 GMT (7:03 p.m. EST Mon.)

The navigation test on the rocket's Inertial Navigation Unit guidance computer has been completed. The INU final alignment is now underway.

MONDAY, DECEMBER 15, 2003
2345 GMT (6:45 p.m. EST)

The mobile service tower is now clear of the rocket and continuing to roll to the parking location for tonight's launch.

Meanwhile, the launch team has begun the C-band system test.

2338 GMT (6:38 p.m. EST)

With three hours left until liftoff time, the command has been given to start rolling the mobile service tower away from the Atlas 3 rocket and into the launch position at pad 36B.

The structure completely encloses the rocket on the launch pad. It is used to erect the vehicle on the pad, give access to all areas of the rocket for workers and provide protection from the weather. It is electrically driven on four-wheel assemblies.

2326 GMT (6:26 p.m. EST)

A poll of the launch team has confirmed everyone is "ready" for mobile service tower rollback. The retraction is slated to begin at 6:38 p.m.

2323 GMT (6:23 p.m. EST)

T-minus 150 minutes and counting. "Man stations for Integrated Launch Operations."

The countdown is on schedule for tonight's launch of the Lockheed Martin Atlas-Centaur rocket on a mission to deliver the 11th and final UHF Follow-On communications satellite into orbit for the United States Navy.

There are two holds, lasting for a total of 45 minutes, built into the countdown at T-minus 105 minutes and T-minus 5 minutes. Liftoff is targeted for 9:38 p.m. EST.

The countdown is being controlled from the Complex 36 Blockhouse where the 120-member team has assembled to oversee the activities leading up to liftoff of this Atlas 3B rocket. The senior management team is housed in the Atlas 5 Spaceflight Operations Center (ASOC), a departure from the past use of NASA's Hangar AE Mission Directors Center for Atlas 2 and 3 rocket launches.

2308 GMT (6:08 p.m. EST)

The Integrated Launch Operations portion of the countdown begins in 15 minutes.

2300 GMT (6:00 p.m. EST)

The sun has set along Florida's East-Central coast on a mostly clear but cool evening. There are no real weather worries for tonight's launch attempt.

Within the next hour, the launch team will begin rolling back the mobile service tower from around the rocket in advance of fueling later in the countdown.

2200 GMT (5:00 p.m. EST)

The entire fleet of Navy Ultra-High Frequency Follow-On (UFO) communications satellites have been launched by the Lockheed Martin Atlas rocket family. Despite a launch failure on the UHF F1 mission in March 1993 by an Atlas 1 rocket, the collaboration between the Navy, satellite-builder Boeing (formerly Hughes) and Lockheed Martin continued.

The UHF F2 satellite was successfully deployed in September 1993, followed by F3 in 1994. Both used the now-retired Atlas 1. The Atlas 2, also now retired, carried the F4 through F8 satellites from 1995 through 1998. The Atlas 2A, also now retired from use, carried F9 in late 1998 and F10 in 1999. Now, the Atlas 3B will loft F11, the last member of the UHF constellation, later tonight.

"It has been a very good partnership with them. They have treated us and our launch team very well. So there is mixed emotion with the fact this is the last of the UHF missions," added Lockheed Martin's Atlas launch director, Adrian Laffitte.

The Atlas 2 and 3 rockets have scored 100 percent mission success in 62 flights, and officials are counting on that record continuing.

"I think it is reassuring to have our spacecraft aboard the launch vehicle we have that has such a tremendous track record. We are looking forward to another perfect launch tonight," said Dave Ryan, vice president and general manager of UHF F11-maker Boeing Satellite Systems.

The countdown is still ticking along smoothly and the weather remains favorable. The two-hour launch window opens at 9:38 p.m. EST.

2100 GMT (4:00 p.m. EST)

The countdown is progressing at Cape Canaveral as engineers and technicians step through the methodical lists of pre-launch activities.

Tonight's launch will be the U.S. Navy's 11th and final Ultra-High Frequency Follow-On (UFO) communications satellite, the culmination of a program that commenced in 1988 and is now valued at over $2 billion. All of the spacecraft were built by Boeing Satellite Systems, formerly Hughes, and launched atop Lockheed Martin Atlas rockets.

"As we prepare to launch this last UFO satellite, I would like to acknowledge that we have had many people over the 15 years supporting this program. They have done an excellent job. Navy civilian and military members, Lockheed and Boeing, together we provided a critical capability to the warfighter," Bob Tarleton, the Navy's manager for communications satellite programs, said at a news conference this morning.

"So with that, I'd like to say: Go Atlas, Go Centaur, Go UFO and Go Navy!"

Liftoff is still set for 9:38 p.m. EST (0238 GMT).

1900 GMT (2:00 p.m. EST)

Every rocket launch comes with a handful of statistics. Here is a look at some of the numbers for tonight's mission:

• This will be the 579th flight of an Atlas booster since 1957
• The 168th launch of a Centaur upper stage (including Atlas and Titan)
• Centaur's 145th flight on Atlas
• The fifth and final Atlas launch in 2003
• The fourth Atlas flight from Cape Canaveral; one occurred earlier this month at Vandenberg Air Force Base, California
• Fourth flight for the Atlas 3-series of rockets since debuting in 2000
• Third time an Atlas 3B has flown and second of 2003
• Seventh flight of the Russian-made RD-180 main engine (used by Atlas 3 and Atlas 5)
• Sixth flight of the "stretched" Centaur upper stage and fifth using a single RL10 engine
• The 61st Boeing Satellite Systems (Hughes) spacecraft launched by Atlas
• The 25th Boeing 601-model spacecraft satellite on Atlas
• The 11th Navy UHF Follow-On communications satellite on Atlas
• If all goes well, this will extend the string of consecutive successful Atlas launches to 68 dating back to 1993

1748 GMT (12:48 p.m. EST)

START COUNTDOWN. Clocks at Cape Canaveral's Launch Complex 36 are beginning to tick down for tonight's launch of the Lockheed Martin Atlas 3B rocket carrying a U.S. Navy communications satellite. Launch is slated to occur at 9:38 p.m. EST (0238 GMT), the opening of a two-hour window.

Throughout the day today the crews in the Complex 36 blockhouse and at pad 36B will proceed through their standard countdown chores needed to ready the Atlas booster and its single-engine, "stretched" Centaur upper stage for launch, as well as the ground systems and UHF F11 spacecraft.

Highlights of activities planned, in the order they are scheduled to be performed, include Centaur propulsion launch preps, powering up the rocket's flight control system, Atlas propulsion and hydraulic systems preps, launch pad umbilical tower and mobile service structure preps, performing the flight control operational test, the internal power test of Atlas-Centaur, performing a navigation test of rocket's guidance computer, Centaur engine igniter checks, starting Centaur helium purges and starting liquid hydrogen and liquid oxygen system final preps.

The Integrated Launch Operations -- the final portion of the countdown in which all members of the launch team participate -- will start at 6:23 p.m. EST (2323 GMT). Retraction of the mobile service tower from around the rocket is slated for 6:38 p.m. EST.

Countdown clocks will enter a planned 30-minute hold at the T-minus 105 minute mark starting at 7:08 p.m. During this time the launch team will have a chance to catch up on any work that could be running behind schedule.

Fueling operations will commence at 7:52 p.m. with super-cold liquid oxygen flowing into the Centaur upper stage. Loading of liquid oxygen into the Atlas booster stage should start at 8:13 p.m. The final segment of fueling will begin at 8:29 p.m. when liquid hydrogen is pumped into the Centaur. The Atlas stage was previously fueled with its supply of RP-1 kerosene propellant.

A final planned hold is scheduled at T-minus 5 minutes for 15 minutes in duration starting at 9:18 p.m. If there are no problems standing in the way of liftoff, the countdown will resume at 9:33 p.m. for an on-time launch.

We will provide play-by-play coverage of the countdown on this page beginning around 6:15 p.m. EST (2315 GMT).

1655 GMT (11:55 a.m. EST)

The latest weather forecast for tonight and the odds for Tuesday and Wednesday is available here.

1640 GMT (11:40 a.m. EST)

All systems remain "go" for tonight's launch of the Lockheed Martin Atlas 3B rocket and the U.S. Navy's UHF Follow-On F11 communications satellite.

"Everything is looking very, very good for launch," Dave Ryan, vice president and general manager of UHF F11-maker Boeing Satellite Systems, told a morning news conference at Cape Canaveral.

Liftoff is scheduled for 9:38 p.m. EST. The launch team will have a two-hour window, extending to 11:38 p.m. EST, to get the rocket airborne.

Air Force meteorologists expect perfect conditions for the liftoff from pad 36B at Cape Canaveral, Florida.

"The frontal system that brought us all the cloudiness and rain yesterday has moved well out of our area," launch weather officer Johnny Weems told reporters. "It doesn't look like there are any concerns for tonight's launch."

The forecast calls for just some scattered clouds, easterly winds and a temperature in the mid-50s F.

"You can't expect any better weather than we expect tonight," Weems said.

SUNDAY, DECEMBER 14, 2003
1700 GMT (12:00 p.m. EST)

The launch weather forecast issued this morning indicates there is less than a 10 percent chance of conditions scrubbing Monday evening's liftoff of the Atlas 3B rocket. Read the complete weather forecast and the odds for Tuesday and Wednesday here.

A pre-launch news conference is scheduled for 10 a.m. EST Monday. We will post an update and countdown preview following the event. And watch this page for live reports throughout the evening!

SATURDAY, DECEMBER 13, 2003
1455 GMT (9:55 a.m. EST)

Devoid of any technical concerns, mission authorities this morning gave approval for Monday's countdown and launch of the Lockheed Martin Atlas 3B rocket to deploy the U.S. Navy's 11th UHF Follow-On communications satellite into Earth orbit.

Officials gathered at Cape Canaveral for the Launch Readiness Review to discuss the progress of pre-flight work and any outstanding problems. The meeting concluded a short time ago by clearing the launch to proceed as scheduled.

"We have no flight constraints. We are working absolutely nothing," Atlas launch director Adrian Laffitte said in a post-LRR interview. "It has been a very clean flow."

Monday's two-hour launch window extends from 9:38 to 11:38 p.m. EST (0238-0438 GMT Tuesday).

Air Force meteorologists continue to predict a 90 percent chance of good launch weather. The only slight worry will be gusty winds at pad 36B. Read the complete weather forecast here.

Backup launch opportunities are available Tuesday and Wednesday evenings, with two-hour windows opening at 9:34 and 9:30 p.m. EST, respectively.

A planned Saturday morning launch of Boeing's Delta 2 rocket carrying a GPS military navigation satellite is expected to slip to Sunday, which would give Atlas another launch slot on the Eastern Range for Thursday evening if needed.

Activities to ready this fourth Atlas 3 rocket, the UHF F11 payload and ground equipment for the countdown have been completed, allowing everyone the chance to take time off this weekend.

"We are giving people the opportunity to enjoy the weekend and catch up on their Christmas shopping," Laffitte said.

"The Atlas 3 processing is a pretty clean, pretty easy flow from a vehicle point-of-view because it has less parts and components."

Clocks begin ticking down at 12:48 p.m. EST Monday.

FRIDAY, DECEMBER 12, 2003

The weather is still looking promising for Monday's launch of the Atlas 3B rocket. The latest forecast, issued this morning, can be seen here.

0001 GMT (7:01 p.m. EST Thurs.)

The last in a long line of communications satellites for the U.S. Navy heads for space Monday night aboard a Lockheed Martin Atlas 3B rocket. Launch from Cape Canaveral's pad 36B is scheduled for 9:38 p.m. EST (0238 GMT). The evening's launch window extends exactly two hours. Read our launch preview story.

Watch this page for live play-by-play updates during Monday's countdown and launch. Also, we will post a status report on Saturday morning following the completion of mission managers' Launch Readiness Review that gives final approval to proceed with the countdown.

THURSDAY, DECEMBER 11, 2003

The early weather forecast for Monday night's launch opportunity is calling for a 90 percent chance of favorable conditions. The only concern will be winds. See the full forecast here.

TUESDAY, NOVEMBER 18, 2003

A U.S. Navy communications satellite is undergoing final pre-launch activities at Cape Canaveral for launch next month aboard a Lockheed Martin Atlas 3B rocket. he Ultra-High Frequency Follow-On F11 spacecraft, built by Boeing, was shipped from its manufacturing plant in El Segundo, California, to Florida's East Coast last week. Read our full story.