BY JUSTIN RAY

Follow the countdown and launch of the Lockheed Martin Atlas 5 rocket with the AMC 16 commercial communications satellite.

0723 GMT (2:23 a.m. EST)

NEW LAUNCH TIME! It has been decided to extend this hold an additional 30 minutes to give the pad crew more time to finish their work of putting the final touches on Complex 41. This decision will delay liftoff accordingly, putting launch at 5:11 a.m. EST (1011 GMT).

0716 GMT (2:16 a.m. EST)

Now half-way through this 30-minute built-in hold. A "ready report" poll of the launch team to ensure everyone is "go" to start cryogenic tanking is scheduled to occur in 10 minutes.

0701 GMT (2:01 a.m. EST)

T-minus 120 minutes and holding. The countdown has entered the scheduled half-hour pause. Clocks are slated to resume at 2:31 a.m. EST. Technicians are continuing to work at the launch pad, progressing through checklists to configure systems and equipment for the remainder of the count. It is estimated that another 30 minutes of work remain. The crews will need to clear the hazard area before fueling operations can begin.

There continues to be a 70 percent chance of acceptable weather conditions during today's launch window of 4:41 to 7:21 a.m. EST. All weather rules are currently "go." But there is cloud cover and rain showers throughout the area.

0645 GMT (1:45 a.m. EST)

First stage hydraulic and propulsion preps are complete.

0644 GMT (1:44 a.m. EST)

Range Safety is beginning the hold-fire checks to ensure the countdown can be halted if a problem arises.

0638 GMT (1:38 a.m. EST)

The flight control system operational test is reported finished. Countdown clocks are nearing a planned 30-minute built-in hold coming up at 2:01 a.m. EST.

0617 GMT (1:17 a.m. EST)

Guidance system testing has been completed.

0541 GMT (12:41 a.m. EST)

The countdown has entered the final four hours for liftoff at 4:41 a.m. EST (0941 GMT) this morning from Cape Canaveral, Florida.

0521 GMT (12:21 a.m. EST)

The Atlas 5 rocket's first stage fuel tank has been fully loaded with its supply of RP-1 kerosene. The stage's liquid oxygen tank will be filled later this morning.

0505 GMT (12:05 a.m. EST)

We've posted a gallery of photographs taken during this evening's rollout of the Atlas 5 rocket. The vehicle was moved from its assembly building to the launch pad around 7:45 p.m. EST. See the pictures here.

0438 GMT (11:38 p.m. EST Thurs.)

The first stage fuel tank is now 70 percent full and continuing to be filled.

0432 GMT (11:32 p.m. EST Thurs.)

The flight control system preps have been completed and an operational test is getting underway in tonight's countdown. Meanwhile, loading of the first stage fuel tank remains in progress.

0423 GMT (11:23 p.m. EST Thurs.)

The RP-1 tank is 20 percent full as first stage fueling continues.

0408 GMT (11:08 p.m. EST Thurs.)

The launch team has been given a "go" to begin pumping RP-1, a highly-refined kerosene propellant, into the Atlas 5 rocket's first stage. The fuel will be consumed by the RD-180 main engine during the initial four-and-a-half minutes of flight.

0310 GMT (10:10 p.m. EST Thurs.)

The Atlas first stage and Centaur upper stage are being powered up at Complex 41 as the launch team guides the countdown through its final hours for the overnight liftoff. There are pockets of clouds and some showers around Central Florida tonight. During rollout of the rocket a couple of hours ago, the moon and stars could be seen from time to time as clouds drifted overhead.

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

ON THE PAD! The Atlas 5 rocket has arrived at the Complex 41 launch pad for Friday morning's predawn liftoff carrying the AMC 16 communications satellite. The 30-minute trip from the Vertical Integration Facility took place under a partly cloud sky.

The two mobile trailers connected to the launching platform, which were part of the convoy during this evening's rollout, soon will be hooked up to power and communications systems at the pad. These trailers provide conditioned air to the payload and communications with the rocket during the roll and throughout the countdown. They are protected from the blast of launch by a concrete structure on the north-side of the platform.

Within the next hour, the auto couplers between the pad and platform will be engaged to route umbilical connections from the ground to the rocket for upcoming fueling of the booster.

At around 9:40 p.m. EST (0240 GMT), the Atlas first stage and Centaur upper stage are scheduled to be powered up. During the following hour, testing of the rocket's guidance system will start along with flight control system preps.

A variety of other standard countdown operations will continue into the overnight hours.

Liftoff remains scheduled for 4:41 a.m. EST (0941 GMT).

0041 GMT (7:41 p.m. EST Thurs.)

Rollout has begun! The Lockheed Martin Atlas 5 rocket is emerging from the 30-story Vertical Integration Facility atop its mobile launching platform.

The white and copper-colored Atlas 5 is being rolled from its assembly building to the launch pad at Cape Canaveral Air Force Station's Complex 41 in preparation for its early morning liftoff.

The 1.4-million pound mobile launching platform moves along rail tracks for the 1,800-foot trip, which should take about 30 minutes to complete.

To learn more about the "clean pad" concept used by Lockheed Martin for the Atlas 5 program, see our complete story.

THURSDAY, DECEMBER 16, 2004
1830 GMT (1:30 p.m. EST)

The Atlas 5 rocket is just a few hours away from leaving its assembly building for the short move to the launch pad at Complex 41. Rollout is expected around 7:30 p.m. EST (0030 GMT) tonight.

The rocket is expected to blast off Friday morning at 4:41 a.m. EST (0941 GMT) from Cape Canaveral Air Force Station. Launch could happen as late as 7:21 a.m. EST (1221 GMT). The only worry is thick clouds spilling into Florida from the Atlantic Ocean.

"We have some cooler air over the warmer waters, which is causing clouds to form. The winds coming from the northeast are bringing those clouds onshore and over our area," said Kathy Winters of the 45th Weather Squadron at Cape Canaveral. "Our main concern for launch is the thick cloud rule. We are not concerned about the pre-launch operations."

If needed, Lockheed Martin has a backup launch opportunity available during the same window on Saturday. Officials could attempt to negotiate another shot on Sunday with the Air Force-controlled Eastern Range that governs all rocket launches from the Cape. But Boeing's delayed Delta 4-Heavy mission is planning to fly early next week, and the Range can support only one mission at a time and spacing is required in between to reset tracking systems.

Launch director Adrian Laffitte said if the Atlas isn't off the ground this weekend the mission would likely be postponed into next year so management, the launch team and the customer can enjoy the holidays.

"On behalf of the the Atlas team, I do want to say we have no intentions of singing Christmas carols on console. So we are ready to launch early tomorrow morning," Laffitte joked at today's pre-launch news conference.

The customer of this fourth Atlas 5 launch is the commercial AMERICOM 16 communications satellite for operator SES AMERICOM. EchoStar's direct-to-home TV system will use the craft's video and broadband relay capability from geostationary orbit.

Watch this page for continuing updates this evening during rollout and overnight throughout the countdown!

1445 GMT (9:45 a.m. EST)

Air Force meteorologists continue to predict a 30 percent chance of violating the thick cloud weather rule during Friday's launch window. See the latest weather forecast here.

WEDNESDAY, DECEMBER 15, 2004

After a hiatus in flights of the new Atlas 5 rocket while Lockheed Martin flew its inventory of older-style boosters, focus returns to the next generation Friday with an early morning launch from Cape Canaveral. Read our full story.

1700 GMT (12:00 p.m. EST)

Launch of Lockheed Martin's Atlas 5 rocket carrying the AMERICOM 16 communications spacecraft remains on schedule for Friday at 4:41 a.m. EST (0941 GMT) from Cape Canaveral, Florida.

"We had the LRR this morning and there are no flight constraints. We're just working the final closeouts of a lot of paperwork. But other than that we're just ready to go," Atlas launch director Adrian Laffitte said.

The rocket is fully assembled in its vertical hangar at Complex 41. Rollout to the launch pad occurs Thursday evening at 7:30 p.m. EST (0030 GMT). Once at the pad, the rocket's first stage will be loaded with kerosene fuel and cryogenic liquid oxygen and the Centaur stage filled with liquid hydrogen and liquid oxygen.

We will provide live play-by-play reports on this page through the countdown and flight.

1430 GMT (9:30 a.m. EST)

The Launch Readiness Review is underway at Cape Canaveral as senior managers meet this morning to verify all systems are "go" for tomorrow night's countdown and Friday's predawn liftoff. We'll post a full update following the meeting.

The weather outlook remains unchanged with a 70 percent chance of favorable conditions. See the latest forecast here.

TUESDAY, DECEMBER 14, 2004

The latest launch weather forecast -- issued this morning -- is available here.

MONDAY, DECEMBER 13, 2004

Launch preparations are continuing at Complex 41 for Friday's planned early morning ascent of the Atlas 5 rocket carrying a commercial communications satellite. The early weather forecast is promising with a 70 percent chance of acceptable conditions. The only concern is thick clouds. See the full forecast here.

MONDAY, DECEMBER 6, 2004

A commercial television broadcast satellite and the rocket that will boost it into space -- Lockheed Martin's Atlas 5 rocket -- were joined together today at Cape Canaveral. Read our full story.

TUESDAY, NOVEMBER 23, 2004

Lockheed Martin's next Atlas 5 rocket and its Cape Canaveral launch team completed a major test Tuesday in preparation for next month's liftoff to deliver a commercial communications satellite into space. Read our full story.

2010 GMT (3:10 p.m. EST)

The countdown rehearsal was successfully conducted today. The rocket will be drained of fuel and rolled back to its assembly building. We'll post a full story later today.

MONDAY, NOVEMBER 22, 2004
2050 GMT (3:50 p.m. EST)

Lockheed Martin has decided to finish the Wet Dress Rehearsal on Tuesday. The rocket will be fully fueled during tomorrow's countdown simulation at the Complex 41 launch pad.

1730 GMT (12:30 p.m. EST)

A Lockheed Martin Atlas 5 rocket was rolled from the assembly hangar to the launch pad early this morning for a countdown dress rehearsal in preparation for its December 16 blastoff from Cape Canaveral.

The launch team will load the booster's first stage with RP-1 kerosene fuel and liquid oxygen and the Centaur upper stage with liquid hydrogen and liquid oxygen during this simulation of launch day activities. The countdown will follow a realistic timeline leading to a mock T-0 this afternoon.

The rocket was put together atop a mobile launch platform inside the Vertical Integration Facility over the past several weeks. The stack was transported via rail to the Complex 41 pad before dawn today.

Following the completion of this test, the rocket will be rolled back to the hangar for final launch processing.

The Atlas 5 will launch the AMC 16 communications satellite for SES Americom. The craft is undergoing its pre-flight campaign at the AstroTech facility in nearby Titusville. It will be moved to the Vertical Integration Facility and mounted atop the rocket in early December.

Liftoff is scheduled for December 16 during a window extending from 4:41 to 6:36 a.m. EST (0941-1136 GMT).

For this fourth flight of the Atlas 5 family, the 521-vehicle configuration will be used. It is distinguished by a five-meter nose cone, two strap-on solid rocket boosters and a single-engine Centaur upper stage. This is the same model used in the most recent Atlas 5 mission.