BY SPACEFLIGHT NOW

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

MONDAY, OCTOBER 30, 2006

The fourth broadcasting spacecraft for XM Satellite Radio successfully ascended to orbit Monday atop a rocket launched from a floating pad in the Pacific Ocean.

The Sea Launch Zenit 3SL booster blasted off at 2348:59.11 GMT (6:48:59.11 p.m. EST) to begin the 61-minute flight to deploy the XM 4 satellite nicknamed "Blues."

"Hooray for Sea Launch!" said John Dealy, XM Satellite Radio senior advisor. "Four times now you have lifted XM -- you lifted Rock, you lifted Roll, you lifted Rhythm and now you've lifted Blues. I think you should change your company's slogan to 'Sea Launch: We lift America's music to new heights.'"

The Zenit 3SL rocket placed the XM 4 "Blues" spacecraft -- weighing 11,448 pounds -- into an elliptical geosynchronous transfer orbit with a low point of 770 miles, a high point of about 22,407 miles and inclination of zero degrees.

"Another successful launch. We're obviously delighted with this afternoon's mission," said Rob Peckham, the president Sea Launch.

The three earlier XM satellites were carried into space by Sea Launch in March 2001, May 2001 and February 2005.

"We are proud to be XM Satellite Radio's launch service provider of choice," Peckham said.

Today's flight was the 23rd for Sea Launch since 1999, the 21st complete success and 9th in a row.

"I also want to take this opportunity to congratulate the Sea Launch team for another outstanding mission. Without the team's expertise and dedication to excellence, we could not have realized today's significant accomplishment," Peckham said.

The Boeing-built XM 4 satellite will use its onboard propulsion to circularize the orbit at geostationary altitude 22,300 miles above the Equator, thereby matching the Earth's rotation and appearing fixed at 115 degrees West longitude.

"We believe (Boeing) has provided us with an excellent satellite. Now it becomes their job to open this baby up, get it to the right orbit and put Blues to work for XM," Dealy said.

The XM 3 and 4 spacecraft (Rhythm and Blues) are revised models from their two predecessors (Rock and Roll), which were deployed in 2001 before Boeing engineers discovered a crippling design flaw that degrades the power-generating capacity as the satellites age. The manufacturer removed the faulty hardware and lengthened XM 3 and 4's solar arrays to overcome the power problem.

The XM satellites serve the United States and Canada, beaming signals to special radios installed in subscribers' cars and portable units that you can take anywhere. The system's seven million subscribers get commercial-free music, sports, talk and comedy channels, as well as traffic and weather information for select metropolitan areas.

A fifth satellite is being built by Space Systems/Loral, which Dealy said Sea Launch will loft.

0053 GMT (7:53 p.m. EST Mon.)

Ground controllers have established contact with the XM 4 "Blues" spacecraft via the Hartebeesthoek tracking station in South Africa.

Blues is a 11,448-pound craft built at the Boeing Satellite Development Center using the 702-model design. It carries a Digital Audio Radio Service payload built by Alcatel Alenia Space.

The XM 3 and 4 satellites (Rhythm and Blues) were constructed and launched as replacements for XM 1 and 2 (Rock and Roll), which have power degradation problems caused by a solar array design flaw.

Sea Launch has deployed all four XM spacecraft, with missions in March 2001, May 2001 and February 2005.

0049 GMT (7:49 p.m. EST Mon.)

T+plus 60 minutes, 59 seconds. SPACECRAFT SEPARATION! The fourth broadcasting spacecraft for XM Satellite Radio has been released from the Block DM-SL upper stage to complete this 23rd Sea Launch flight.

The XM 4 craft, nicknamed Blues, joins the previously-launched Rock, Roll and Rhythm satellites in space to provide the radio programming to seven million subscribers across the U.S. and Canada.

0044 GMT (7:44 p.m. EST Mon.)

T+plus 55 minutes. Deployment of the spacecraft from the upper stage is just over 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.

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

T+plus 50 minutes, 14 seconds. The Block DM-SL's 11D58M main engine has shut down, completing the powered phase of todays's launch. The stage will now coast for approximately 10 minutes before deploying the XM 4 satellite.

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

T+plus 49 minutes. Engine pressured reported normal. Just over a minute left to go in this burn.

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

T+plus 45 minutes. The Block DM-SL is stable as this six-minute burn proceeds.

0033 GMT (7:33 p.m. EST Mon.)

T+plus 44 minutes, 6 seconds. The upper stage has reignited to send XM 4 into geosynchronous transfer orbit.

0024 GMT (7:24 p.m. EST Mon.)

T+plus 35 minutes. The vehicle is now soaring above the Atlantic Ocean.

0013 GMT (7:13 p.m. EST Mon.)

T+plus 24 minutes. Twenty minutes from engine restart. The rocket is now coasting over South America.

0005 GMT (7:05 p.m. EST Mon.)

T+plus 16 minutes. The upper stage will coast in this orbit until the Block DM-SL reignites at T+plus 44 minutes for the firing to achieve geosynchronous transfer orbit. The burn should last about six minutes. Deployment of XM 4 to complete today's launch is expected about 61 minutes after liftoff.

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

T+plus 14 minutes, 10 seconds. Engine cutoff. The Block DM-SL upper stage has completed its first burn, injecting the motor and attached XM 4 spacecraft into a temporary parking orbit around Earth.

0002 GMT (7:02 p.m. EST Mon.)

T+plus 13 minutes. The vehicle has reached orbital velocity. About a minute remains in this planned upper stage burn to reach a parking orbit of 112 x 1,007 miles.

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

T+plus 12 minutes. The Block DM-SL main engine is burning a mixture of highly refined kerosene propellant and supercold liquid oxygen.

2359 GMT (6:59 p.m. EST)

T+plus 10 minutes. The Block DM-SL is stable and firing normally. This burn of the upper stage will last five-and-a-half minutes.

2357 GMT (6:57 p.m. EST)

T+plus 8 minutes, 47 seconds. The Block DM-SL upper stage has ignited for today's first of two firings to propel the XM 4 spacecraft from the current suborbital trajectory to geosynchronous transfer orbit.

2357 GMT (6:57 p.m. EST)

T+plus 8 minutes, 30 seconds. The second stage vernier engines have shut down and jettisoning of the spent stage has occurred. It will impact the Pacific approximately 2,900 miles downrange from the launch platform.

2357 GMT (6:57 p.m. EST)

T+plus 8 minutes. Venier engine pressures are normal.

2356 GMT (6:56 p.m. EST)

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

2356 GMT (6:56 p.m. EST)

T+plus 7 minutes. The second stage is throttling down in preparation for engine cutoff.

2355 GMT (6:55 p.m. EST)

T+plus 6 minutes. Second stage engine performance is normal as the motor continues to fire.

2354 GMT (6:54 p.m. EST)

T+plus 5 minutes. The rocket remains stable on the second stage propulsion.

2353 GMT (6:53 p.m. EST)

T+plus 4 minutes, 30 seconds. NASA's Tracking and Data Relay Satellite System has acquired the vehicle's signal to receive telemetry for transmission to Sea Launch ground engineers. The second stage is still firing.

2353 GMT (6:53 p.m. EST)

T+plus 4 minutes. The rocket's payload fairing, or nose cone, has been jettisoned. It protected the satellite cargo during atmospheric ascent. The nose cone will impact the Pacific about 650 miles downrange.

2352 GMT (6:52 p.m. EST)

T+plus 3 minutes. Flight remains normal for the Sea Launch rocket following today's liftoff at 2348:59.11 GMT. The second stage engine continues to burn.

2351 GMT (6:51 p.m. EST)

T+plus 2 minutes, 45 seconds. The second stage engine has been ignited for its firing.

2351 GMT (6:51 p.m. EST)

T+plus 2 minutes, 35 seconds. The first stage RD-171 engine has shut down and the spent stage was jettisoned. It will impact the Pacific Ocean approximately 485 miles downrange from the Odyssey launch platform.

2350 GMT (6:50 p.m. EST)

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

2349 GMT (6:49 p.m. EST)

T+plus 45 seconds. The 20-story Zenit 3SL rocket is riding the thrust of the first stage main engine. The Russian-made engine has four nozzles and powers the rocket for the first two-and-a-half minutes of flight.

2349 GMT (6:49 p.m. EST)

LIFTOFF! Liftoff of the Zenit rocket launching the fourth broadcasting spacecraft for XM Satellite Radio.

2348 GMT (6:48 p.m. EST)

T-minus 1 minute. Final status checks are being taken as the automated launch sequence enters the final 60 seconds.

2346 GMT (6:46 p.m. EST)

T-minus 3 minutes. The payload is confirmed on internal power and "go" for launch.

2341 GMT (6:41 p.m. EST)

T-minus 8 minutes and counting. Sea Launch reports everything is looking good for liftoff at 2349 GMT.

2337 GMT (6:37 p.m. EST)

T-minus 12 minutes and counting. Sea Launch is counting down the final minutes for today's liftoff of the Zenit rocket and XM 4 spacecraft.

FRIDAY, OCTOBER 27, 2006

Launch has been rescheduled for Monday at 2349 GMT (6:49 p.m. EST) at the opening of a 58-minute window.

"The Sea Launch team has determined the cause of the off-nominal data received from our automated launch support equipment that resulted in a halt to the launch countdown on Oct. 26. The team has implemented corrective action and is ready to proceed with launch operations," the company said in a statement tonight.

0115 GMT (9:15 p.m. EDT Thurs.)

"Due to off-nominal data from its automated launch support equipment, Sea Launch today halted the launch of the XM-4 broadcast satellite," the company said in a statement released a short time ago.

"Following the direction to stop the countdown, the launch team immediately implemented system safing and securing operations, according to procedure. Both the spacecraft and the launch vehicle are in excellent condition."

The statement did not indicate when launch will be rescheduled.

THURSDAY, OCTOBER 26, 2006
2349 GMT (7:49 p.m. EDT)

Normal post-scrub safing procedures are underway after the launch countdown was halted about minute before liftoff time tonight. There is no word from Sea Launch on the reason for this stoppage of the countdown or when another liftoff attempt can be made.

2348 GMT (7:48 p.m. EDT)

HOLD. The countdown has been halted.

2348 GMT (7:48 p.m. EDT)

T-minus 1 minute. Final status checks are being taken as the automated launch sequence enters the final 60 seconds.

2346 GMT (7:46 p.m. EDT)

T-minus 3 minutes. The payload is confirmed on internal power and ready for launch. And the erector arm has returned to the hangar.

2342 GMT (7:42 p.m. EDT)

T-minus 7 minutes and counting. All systems appear "go" for liftoff from the Odyssey launch platform.

2337 GMT (7:37 p.m. EDT)

T-minus 12 minutes and counting. The transporter/erector arm is pulling away from the Sea Launch Zenit 3SL rocket right now. The arm was used to roll the rocket out of the environmentally-controlled hangar atop the Odyssey platform and lift the rocket upright.

The arm is being lowered to the platform deck where 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 uprange.

THURSDAY, OCTOBER 26, 2006

A Sea Launch Zenit 3SL rocket will launch another broadcasting spacecraft for XM Satellite Radio tonight from a floating platform stationed in the equatorial waters of the Pacific Ocean.

Liftoff is scheduled for 2349 GMT (7:49 p.m. EDT). The available launch window extends 58.

The Odyssey launch platform is positioned along the Equator at 154 degrees West longitude. The rocket will fly eastward, ultimately releasing its payload high above eastern Africa.

The Sea Launch fleet reached the launch site a few days ago after steaming for more than a week from the company's home port in Long Beach, California. The ocean-going launch pad known as Odyssey set sail first, followed later by the departure of the Sea Launch Commander vessel, which houses the management, official guests and launch control center.

Odyssey's ballast tanks were filled with seawater upon arrival, dropping the converted Norwegian oil-drilling platform to the launch depth of 65 feet. Control teams also commenced the standard 72-hour countdown. The Sea Launch Commander then pulled alongside Odyssey to allow workers to easily transfer between the two ships. The Zenit 3SL rocket was rolled out from its transport hangar aboard Odyssey and erected on the launch pedestal yesterday.

The three-stage Zenit booster - making its 23rd flight in this configuration - will take just over an hour to complete its role to deliver the XM 4 payload into a planned orbit with a low point of 767 miles and a high point of about 22,479 miles. The injection orbit's inclination will be zero degrees.

XM 4 will use its propulsion system to gradually raise its orbit to geostationary altitude, where its velocity will match that of Earth's rotation. The satellite will be positioned along the Equator at 115 degrees West longitude.

Controllers will spend the last hours of today's launch countdown making final preparations to the rocket, payload and ground infrastructure. The Sea Launch Commander will pull away from the launch platform to a safe viewing distance about three miles away.

Fueling operations will get underway about two-and-a-half hours prior to the scheduled launch time. A mix of refined kerosene and liquid oxygen comprise the propellant used by all three stages of the launch vehicle.

After liftoff, the Zenit 3SL will fly downrange on a due east trajectory hugging the Equator. The first stage's Ukrainian four-chamber RD-171 engine ramps up to a maximum of 1.6 million pounds of thrust during its burn lasting two-and-a-half minutes. After first stage separation, the second stage's RD-120 powerplant will come to life. During the second stage firing, the payload fairing shielding the XM 4 satellite during the flight through the denser lower atmosphere will be jettisoned.

Eight minutes, 31 seconds after blastoff is the point when the second stage will separate from the Block-DM upper stage and payload. Ten seconds later, the Block-DM will ignite for an five-and-a-half minute burn to place itself in a temporary parking orbit with a low point of 112 miles and a high point of 1,007 miles. After an extended coast phase, the stage will ignite again at T+Plus 44 minutes, 7 seconds to inject XM 4 into its targeted geostationary transfer orbit. Spacecraft separation is expected 61 minutes after liftoff.

Check this page during the launch for live updates on the mission's progress.