BY SPACEFLIGHT NOW

Follow the countdown and flight of the Sea Launch Zenit 3SL rocket with the third broadcasting spacecraft for XM Satellite Radio. Reload this page for the latest on the mission.

TUESDAY, MARCH 1, 2005

With its popularity growing and new subscribers steadily signing up, XM Satellite Radio successfully deployed its third broadcasting spacecraft Monday night using a sea-launched rocket from a platform floating in equatorial waters of the Pacific. Read our full story.

0453 GMT (11:53 p.m. EST Mon.)

T+plus 62 minutes. Ground controllers have acquired telemetry from the XM 3 satellite via a South African station, confirming the spacecraft is functioning following launch into space.

0451 GMT (11:51 p.m. EST Mon.)

T+plus 60 minutes, 55 seconds. SPACECRAFT SEPARATION! The XM 3 radio broadcasting spacecraft has been released from the Block DM-SL upper stage to complete this 15th Sea Launch flight.

Controllers expect to acquire the first signals from the newly-launched satellite in a few moments via a ground tracking station in Africa.

0450 GMT (11:50 p.m. EST Mon.)

T+plus 59 minutes. XM 3 will be separating from the rocket will flying above the coast of Gabon, Africa.

0446 GMT (11:46 p.m. EST Mon.)

T+plus 56 minutes. Deployment of the spacecraft from the upper stage is about five minutes away. During this coast period between completion of the Block DM-SL stage's burn and spacecraft separation, the stage is providing the necessary control and orientation for payload release.

0442 GMT (11:42 p.m. EST Mon.)

T+plus 51 minutes. The geosynchronous transfer orbit has been reached, Sea Launch says.

0441 GMT (11:41 p.m. EST Mon.)

T+plus 50 minutes, 16 seconds. The Block DM-SL's main engine has shut down, completing the powered phase of tonight's launch. The stage will now coast for about 10 minutes before deploying the XM 3 satellite.

0440 GMT (11:40 p.m. EST Mon.)

T+plus 49 minutes. This three-minute maneuver continues as planned.

0439 GMT (11:39 p.m. EST Mon.)

T+plus 48 minutes. The engine pressures are normal.

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

T+plus 47 minutes, 14 seconds. Ignition! The Block DM-SL upper stage is firing its engine to raise the altitude into the targeted geosynchronous transfer orbit.

0437 GMT (11:37 p.m. EST Mon.)

T+plus 46 minutes. The upper stage is reported to be stable and flying normally as it prepares for the next firing.

0428 GMT (11:28 p.m. EST Mon.)

T+plus 37 minutes. The coast period continues. The next phase of the launch begins in about 10 minutes with re-ignition of the upper stage.

0409 GMT (11:09 p.m. EST Mon.)

T+plus 18 minutes. The upper stage will coast in the low-altitude orbit until the Block DM-SL reignites at T+plus 47 minutes for a scheduled three-minute firing to achieve geosynchronous transfer orbit. Deployment of XM 3 to complete tonight's launch is expected about 61 minutes after liftoff.

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

T+plus 17 minutes, 10 seconds. Engine cutoff. The Block DM-SL upper stage has completed its first burn this evening, injecting the motor and attached XM 3 spacecraft into a temporary parking orbit around Earth.

0407 GMT (11:07 p.m. EST Mon.)

T+plus 16 minutes, 40 seconds. The upper stage is stable and operating properly as this first firing nears its conclusion.

0405 GMT (11:05 p.m. EST Mon.)

T+plus 14 minutes. Engine pressures are reported normal.

0403 GMT (11:03 p.m. EST Mon.)

T+plus 12 minutes. Sea Launch is not reporting any problems with the upper stage burn.

0401 GMT (11:01 p.m. EST Mon.)

T+plus 10 minutes. The upper stage will fire for more than 8 minutes to achieve an initial parking orbit around Earth.

0359 GMT (10:59 p.m. EST Mon.)

T+plus 8 minutes, 45 seconds. The Block DM-SL upper stage has ignited for its first of two firings this evening that will propel the XM 3 spacecraft into geosynchronous transfer orbit.

0359 GMT (10:59 p.m. EST Mon.)

T+plus 8 minutes, 33 seconds. The second stage vernier engines have shut down and the spent stage has been jettisoned. It will impact the Pacific about 4,560 km downrange from the launch platform.

0358 GMT (10:58 p.m. EST Mon.)

T+plus 7 minutes, 10 seconds. The second stage RD-120 main engine has shut down. The vernier steering engines are still burning as planned.

0357 GMT (10:57 p.m. EST Mon.)

T+plus 6 minutes, 50 seconds. The second stage is throttling down in preparation for engine cutoff.

0357 GMT (10:57 p.m. EST Mon.)

T+plus 6 minutes. Second stage main engine and verniers continue to fire.

0355 GMT (10:55 p.m. EST Mon.)

T+plus 4 minutes, 30 seconds. The vehicle remains stable and the engine pressures are normal.

0354 GMT (10:54 p.m. EST Mon.)

T+plus 3 minutes, 45 seconds. The command has been issued to jettison the rocket's payload fairing, or nose cone. It protected the satellite cargo during atmospheric ascent. The nose cone will impact the Pacific about 1,000 km downrange.

0354 GMT (10:54 p.m. EST Mon.)

T+plus 3 minutes. Good performance for the second stage, Sea Launch says.

0353 GMT (10:53 p.m. EST Mon.)

T+plus 2 minutes, 35 seconds. The second stage engine has been ignited for its firing.

0353 GMT (10:53 p.m. EST Mon.)

T+plus 2 minutes, 30 seconds. The first stage RD-171 engine has shut down and the spent stage was jettisoned. It will impact the Pacific Ocean approximately 780 km downrange from the Odyssey launch platform.

0352 GMT (10:52 p.m. EST Mon.)

T+plus 1 minute, 30 seconds. The official liftoff time was 0351:59.17 GMT.

0352 GMT (10:52 p.m. EST Mon.)

T+plus 1 minute, 10 seconds. The vehicle has passed through the region of maximum dynamic pressure.

0351 GMT (10:51 p.m. EST Mon.)

T+plus 30 seconds. A normal flight is being reported as the rocket maneuvers to the proper heading to fly eastward along the equator.

0351 GMT (10:51 p.m. EST Mon.)

LIFTOFF! Liftoff of the Sea Launch Zenit 3SL rocket carrying the third broadcasting spacecraft for XM Satellite Radio.

0350 GMT (10:50 p.m. EST Mon.)

T-minus 1 minute and counting. Final approval for liftoff is being given.

0349 GMT (10:49 p.m. EST Mon.)

T-minus 2 minutes and counting. The engine start preparations are beginning to ready the first stage RD-171 powerplant for ignition. The Russian-made engine has four nozzles and powers the rocket for the first two-and-a-half minutes of flight.

0345 GMT (10:45 p.m. EST Mon.)

T-minus 6 minutes. Rocket and XM 3 spacecraft systems are being reported "go" for launch.

0344 GMT (10:44 p.m. EST Mon.)

T-minus 7 minutes. The transporter/erector has moved away from the rocket. Liquid oxygen replenishment to the vehicle is being secured.

0341 GMT (10:41 p.m. EST Mon.)

T-minus 10 minutes and counting. Liftoff time is fast approaching for Sea Launch's Zenit 3SL rocket topped with the XM 3 radio satellite. After waiting nearly a week to resolve technical problems with the vehicle that scrubbed the last launch attempt, the countdown is proceeding to liftoff at 0351 GMT for the hour-long flight to deploy the payload into orbit.

MONDAY, FEBRUARY 28, 2005

A Zenit rocket will try again tonight to launch a replacement spacecraft for the XM Satellite Radio system after two earlier scrubs. Over the weekend, the rocket was rolled out and erected as Sea Launch pressed ahead with this latest countdown.

Liftoff is scheduled for 0351 GMT (10:51 p.m. EST) this evening at the opening of a one-hour launch window.

FRIDAY, FEBRUARY 25, 2005

Sea Launch continues to keep its Zenit rocket grounded due to the technical trouble uncovered during the final minutes of Tuesday night's countdown. Crews have lowered the rocket from its launch stand and rolled it back to the protective hangar on the floating Odyssey platform. A new launch date has not been established.

WEDNESDAY, FEBRUARY 23, 2005
0501 GMT (12:01 a.m. EST)

Tuesday night's blastoff of the Sea Launch Zenit 3SL rocket carrying the XM 3 radio broadcasting satellite was aborted with seven minutes remaining in the countdown because of trouble with the booster.

"An out-of-specification condition was identified on the launch vehicle and Sea Launch is in the process of rescheduling the launch," the firm said in a post-scrub statement.

Sea Launch says liftoff will occur no sooner than Friday night.

0347 GMT (10:47 p.m. EST Tues.)

SCRUB. Sea Launch says the mission director has ordered an abort of tonight's countdown to liftoff. There was no immediate reason given by Sea Launch to explain what caused the mission to be scrubbed for the day. Also, it is not clear when another launch attempt will be made.

0346 GMT (10:46 p.m. EST Tues.)

HOLD. The countdown has been stopped.

0342 GMT (10:42 p.m. EST Tues.)

T-minus 10 minutes and counting. All systems are "go" for liftoff as scheduled this evening. The launch site weather conditions at the equator are acceptable. Winds are 12 knots from east and the temperature is 72 degrees F.

0337 GMT (10:37 p.m. EST Tues.)

T-minus 15 minutes. The transporter/erector arm is starting to retract from the rocket. The arm was used to roll the rocket out of the environmentally-controlled hangar atop the Odyssey platform and lift the rocket upright. Once the arm is lowered to the platform deck, it will be returned to the hangar and the doors closed for launch.

Fueling operations have been completed aboard the Odyssey platform. Over the past couple of hours, the rocket was loaded with kerosene propellant and cryogenic liquid oxygen. The platform was cleared of all workers prior to this hazardous activity, with all personnel moved to the Sea Launch Commander ship safely positioned about three miles away.

TUESDAY, FEBRUARY 22, 2005

Sea Launch reports that final preparations are underway for tonight's flight of the Zenit 3SL rocket carrying the XM 3 radio broadcasting satellite. Liftoff remains targeted for 0352 GMT (10:52 p.m. EST) at the opening of a 60-minute launch window. Watch this page for live updates during the hour-long ascent to orbit.

MONDAY, FEBRUARY 21, 2005

After several days spent waiting for weather and sea conditions to improve, Sea Launch has rescheduled liftoff of its Zenit rocket from the Pacific Ocean for 0352 GMT (10:52 p.m. EST) on Tuesday night.

In preparation for the initial launch attempt last week, the rocket was rolled out of the enclosed hangar and erected upright atop the converted oil-drilling rig that serves as the launch platform. But during the delay, the booster was lowered horizontally and moved back into the hangar. As the new countdown now proceeds for Tuesday's launch, the vehicle today was returned to the launch mount and stood up.

THURSDAY, FEBRUARY 17, 2005

DELAYED AGAIN. The Sea Launch mission carrying the XM 3 satellite will remain on hold pending improved wave, ocean current and wind conditions. A new launch date has not been announced.

WEDNESDAY, FEBRUARY 16, 2005

DELAY. Tonight's scheduled liftoff of the XM Radio spacecraft aboard the Zenit 3SL rocket has been scrubbed due to unfavorable sea conditions at the Pacific Ocean launch site. The launch has been rescheduled for Thursday night at 0353 GMT (10:53 p.m. EST).

TUESDAY, FEBRUARY 15, 2005

A Sea Launch Zenit 3SL rocket is standing atop its ocean-going platform in the Pacific Ocean for Wednesday night's blastoff to deliver a replacement spacecraft into orbit for XM Satellite Radio.

The Odyssey platform and the Sea Launch Commander control ship both reached the launch site -- located at 154 degrees West longitude along the equator -- over the weekend after journeying from the Sea Launch home port in Long Beach, California.

The Zenit booster was rolled out of its protective hangar aboard Odyssey and erected vertically onto its launch pedestal today as final countdown preparations continued.

Liftoff is scheduled for 0353 GMT (10:53 p.m. EST) at the opening of a 60-minute launch window.

The 15th Sea Launch flight is supposed to deploy the 10,360-pound XM 3 satellite into a highly elliptical geosynchronous transfer orbit about 61 minutes after liftoff.

Manufactured by Boeing Satellite Systems, XM 3 is destined to replace one of XM Satellite Radio's two defective spacecraft already in orbit. The two original satellites were built using Boeing's 702-model, but those massive craft were found to suffer a design flaw that degrades the onboard power supply over time. As a result, the redesigned XM 3 is being launched.

After deployment from the Sea Launch rocket, the satellite will perform a series of orbit-raising maneuvers to reach its orbital slot in geostationary orbit 22,300 miles above the equator at 85 degrees West longitude.

XM is the leading satellite radio service in the U.S. The system broadcasts digital programming to subscribers from coast to coast, including 68 commercial-free music channels, more than 40 channels of sports, talk, comedy, children's and entertainment programming, and 21 channels of traffic and weather information for select metropolitan areas.

Looking ahead to the launch day activities, fueling of the rocket with its highly refined kerosene and liquid oxygen propellant begins in the last hours leading up to blastoff. The erector arm will be retracted and lowered away from the vehicle about 17 minutes before launch.

The first stage will burn for two-and-a-half minutes before shutting down and separating as the second stage ignites. The nose cone shielding the payload will be jettisoned 75 seconds later. The second stage will continue firing until about 8 minutes, 30 seconds into flight, followed by stage separation and ignition of the Block DM-SL upper stage for the first of two firings of the launch.

The upper stage's first burn will last eight-and-a-half minutes to reach a temporary parking orbit around Earth. The stage and attached satellite then coast through space for 30 minutes before the engine is restarted for a three-minute burn to place the spacecraft into its intended orbit.

Spacecraft separation is slated for 60 minutes, 58 seconds after liftoff.