BY SPACEFLIGHT NOW

Follow the preparations and launch of the Russian Proton rocket carrying the Intelsat 903 communications satellite. Reload this page for the very latest on the mission.

SUNDAY, MARCH 31, 2002

A Russian Proton rocket successfully transported a commercial satellite into orbit Saturday that will provide telecommunications services to the Americas, Europe, Africa and the Middle East. Read our full launch story.

0020 GMT (7:20 p.m. EST Sat.)

SPACECRAFT SEPARATION. The Intelsat 903 satellite has been placed into orbit successfully today by a Russian Proton rocket. Deployment from the Block DM upper stage occurred a short time ago after the rocket motor performed its third firing.

Built by Space Systems/Loral, the Intelsat company will operate the satellite to provide telecommunications services to the Americas, Europe, Africa and the Middle East. Intelsat 903 will be maneuvered to geostationary orbit 36,000 km (22,300 miles) above the equator at 34.5 degrees West, replacing the aging Intelsat 601 spacecraft in Intelsat's Atlantic Ocean Region coverage zone.

We'll have a wrap up story a little bit later tonight.

SATURDAY, MARCH 30, 2002

For our Spaceflight Now Plus subscribers, here are some movies of today's mission:

Video coverage for subscribers only:
   VIDEO: PROTON ROCKET LIFTS OFF WITH INTELSAT 903 QT or RV
   VIDEO: PRE-LAUNCH PROCESSING OF PROTON ROCKET QT or RV
   VIDEO: PROTON ERECTED ON THE LAUNCH PAD QT or RV
   VIDEO: NARRATED LAUNCH SEQUENCE MOVIE QT or RV
   VIDEO: INTELSAT 903 MISSION OVERVIEW QT or RV

1915 GMT (2:15 p.m. EST)

T+plus 1 hour, 55 minutes. The second firing of the Block DM upper stage was performed successfully, ILS confirms. The rocket motor and attached Intelsat 903 satellite are now in a lengthy coast period through space. The third and final Block DM burn is expected at T+plus 6 hours and 14 minutes and will last for about 90 seconds. Spacecraft separation to complete today's mission is scheduled for T+plus 6 hours and 43 minutes.

Check back for confirmation of spacecraft separation.

1742 GMT (12:42 p.m. EST)

T+plus 17 minutes. International Launch Services reports that the first Block DM burn has been completed successfully. The stage and Intelsat 903 are now in another coast period that will last nearly an hour.

Highlights of events yet to come will include two more firings by the Block DM. The first is scheduled for T+plus 73 minutes, 9 seconds to raise the altitude from the current low-altitude circular parking orbit to an egg-shaped loop reaching about 35,000 km high at one end. The rocket will coast up to that high point before the second burn at T+plus 6 hours, 14 minutes that will raise the orbit's low end and reduce inclination from the equator.

Separation of Intelsat 903 to complete this launch is expected around T+plus 6 hours, 43 minutes with the satellite being deployed into orbit of 3,500 km on the low end and 35,786 km on the high end with an inclination of 25 degrees to the equator.

We'll pause our coverage at this point. Check back later for updates as we get them from ILS.

1741 GMT (12:41 p.m. EST)

T+plus 16 minutes. The first of three firings by the Block DM upper stage is now underway. This approximate minute burn will place the stage and attached the Intelsat 903 spacecraft into a 161-km parking orbit.

1737 GMT (12:37 p.m. EST)

T+plus 12 minutes. The Block DM upper stage and payload are continuing in their coast period before the first of three burns by the motor.

1735 GMT (12:35 p.m. EST)

T+plus 10 minutes, 5 seconds. The spent third stage has been jettisoned. The Block DM upper stage and attached Intelsat 903 spacecraft are now flying on their own. The Block DM will ignite in about five minutes for a 68-second burn to achieve a low-altitude parking orbit around Earth.

1734 GMT (12:34 p.m. EST)

T+plus 9 minutes, 50 seconds. The third stage RD-0210 engine shutdown has occurred.

1734 GMT (12:34 p.m. EST)

T+plus 9 minutes, 15 seconds. Altitude 137 km, downrange 1,779 km.

1733 GMT (12:33 p.m. EST)

T+plus 8 minutes, 40 seconds. About one minute left in the third stage burn. Altitude 135.5 km, downrange distance 1550 km.

1732 GMT (12:32 p.m. EST)

T+plus 7 minutes, 40 seconds. Good pressure readings from the third stage main engine. Altitude 136.8 km, 1222 km downrange.

1731 GMT (12:31 p.m. EST)

T+plus 6 minutes, 45 seconds. Third stage burn continues normally. Altitude 135 km, 950 km downrange.

1731 GMT (12:31 p.m. EST)

T+plus 6 minutes, 5 seconds. The payload fairing enclosing the Intelsat 903 spacecraft atop the rocket has been jettisoned.

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

T+plus 5 minutes, 56 seconds. The second stage has shut down and separated. Third stage engine ignition confirmed.

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

T+plus 5 minutes, 20 seconds. Guidance and control system reported normal. Altitude 112 km, 481 km downrange.

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

T+plus 5 minutes. Pitch, yaw and roll programs are normal.

1729 GMT (12:29 p.m. EST)

T+plus 4 minutes. Guidance and control system reported normal. Altitude 98.1 km, 333 km downrange.

1728 GMT (12:28 p.m. EST)

T+plus 3 minutes. Smooth flight for the Proton so far. No problems reported. All vehicle systems are normal. Altitude 76.5 km, downrange distance 196 km.

1727 GMT (12:27 p.m. EST)

T+plus 2 minutes, 30 seconds. Good thrust reported on the second stage engines.

1727 GMT (12:27 p.m. EST)

T+plus 2 minutes, 15 seconds. The four RD-0210 second stage engines have ignited. And the spent first stage has separated.

1726 GMT (12:26 p.m. EST)

T+plus 90 seconds. Altitude 21.8 km, 23 km downrange.

1726 GMT (12:26 p.m. EST)

T+plus 60 seconds. Nearing the period of maximum dynamic pressure. Engines at 100 percent thrust.

1725 GMT (12:25 p.m. EST)

T+plus 45 seconds. Good first stage reported.

1725 GMT (12:25 p.m. EST)

T+plus 30 seconds. The Proton rocket has performed its roll maneuver to achieve the proper launch heading. All six RD-253 first stage liquid-fueled engines are firing.

1725 GMT (12:25 p.m. EST)

LIFTOFF! Liftoff of the commercial Proton rocket carrying the Intelsat 903 telecommunications satellite.

1724 GMT (12:24 p.m. EST)

T-minus 1 minute. Now 60 seconds away from launch of the Proton rocket and Intelsat 903 satellite. All systems are go. Ignition key has been activated.

The engine start command will be issued by the launch sequencer at T-minus 2.5 seconds. The six first stage engines will be ignited at T-minus 1.6 seconds and commanded to 40 percent thrust. The thrust level is then increased to 100 percent at T-0 seconds. The liftoff confirmation is expected at T+0.57 seconds.

This engine start sequence allows for verification that all six powerplants are running normally before committing the Proton to launch.

1723 GMT (12:23 p.m. EST)

T-minus 2 minutes and counting. The Block DM upper stage readiness for flight is now being verified. No problems have been reported during the final countdown to liftoff.

1722 GMT (12:22 p.m. EST)

T-minus 3 minutes and counting. The Intelsat 903 spacecraft team has reported that the satellite is clear to launch. The Proton core vehicle has also been verified ready for flight.

1721 GMT (12:21 p.m. EST)

T-minus 4 minutes and counting. The enable key of the launch sequencer is being turned to the "on" position as the countdown continues to liftoff at 1725 GMT.

1720 GMT (12:20 p.m. EST)

T-minus 5 minutes and counting. The Proton rocket's first three stages -- which comprise the "core vehicle" -- are being checked for final confirmation they are ready for launch.

1715 GMT (12:15 p.m. EST)

T-minus 10 minutes and counting. Now inside the final 10 minutes to liftoff of the International Launch Services Proton rocket. This will be ILS' 22nd Proton mission dating back to 1996. All but one of the previous launches have been successful. It also marks the 291st Russian Proton rocket launch overall, extending back to 1965, and the first of 2002.

1710 GMT (12:10 p.m. EST)

T-minus 15 minutes and counting. There are no technical problems being reported and the weather is acceptable for today's liftoff at 1725 GMT. The launch window extends for just 12 seconds.

1705 GMT (12:05 p.m. EST)

T-minus 20 minutes and counting. The Proton rocket weighs about 1.5 million pounds as it sits on the launch pad. The Loral-built Intelsat 903 spacecraft accounts for 10,421 pounds of the weight. At launch the Proton's six first stage engines will fire together to propel the massive, 188-foot tall rocket into the evening skies at Baikonur.

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

T-minus 25 minutes and counting. The countdown is currently under computer sequencer control, which will continue through liftoff. The final updates to the rocket's guidance computer were recently performed. The Proton rocket and Intelsat 903 spacecraft are both "go" for launch at this time.

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

T-minus 30 minutes and counting. Officials report all systems remain "go" for an on-time launch at 1725 GMT.

1645 GMT (11:45 a.m. EST)

T-minus 40 minutes. The mobile service tower has been retracted as the countdown continues for today's planned 1725 GMT (12:25 p.m. EST) launch of the Proton K rocket from the Baikonur Cosmodrome.

1625 GMT (11:25 a.m. EST)

T-minus 1 hour and counting. A Russian Proton rocket is one hour away from blastoff to deliver the Intelsat 903 commercial telecommunications satellite into space. The three-stage Proton core vehicle and Block DM upper stage are now fully fueled, a process that began about six hours before launch time. At this point in the countdown, the pad's mobile service tower should have been rolled away from the rocket in the past few minutes.

Liftoff is still slated to occur at 1725 GMT from Complex 81's pad 23 at the Baikonur Cosmodrome in Kazkhstan.

SATURDAY, MARCH 30, 2002

The Russian Proton rocket with the Intelsat 903 communications satellite aboard remains scheduled for launch today from the Baikonur Cosmodrome in Kazakhstan.

Liftoff is slated to occur at 1725 GMT. That equates to 12:25 p.m. EST in the Eastern U.S., 8:25 p.m. Moscow time and 10:25 p.m. local time at Baikonur.

We'll have live status updates on the final countdown and launch starting about a half-hour before liftoff.

THURSDAY, MARCH 28, 2002

The first commercial launch of a Proton rocket in 9 months is set to lift off from the desert steppes of Kazakhstan Saturday, lofting the fourth satellite in the newest series of communications spacecraft for international operator Intelsat.

Plans call for the marathon six-hour, 43-minute flight to begin at 1725 GMT (12:25 p.m. EST) from the Baikonur Cosmodrome.

A Khrunichev Proton K rocket with an RSC Energia Block DM upper stage will be used to haul the Intelsat 903 communications satellite into geostationary transfer orbit.

It will mark the 22nd Proton launch marketed under the auspices of International Launch Services, a joint U.S./Russian venture formed in 1995 to globally market Atlas and Proton rockets.

The last ILS commercial Proton launch was last June. The lengthy gap between flights was caused by delays in preparing satellite payloads for flight -- Intelsat 903 and the DirecTV-5 craft, now slated to fly later this spring, were both supposed to launch late last fall.

After lifting off from pad 23 at Baikonur's complex 81, the Proton rocket's first stage will fire for two minutes before shutting down and separating. The second stage will then burn for 3 1/2 minutes. At T+5 minutes, 30 seconds, the second stage will cut off and the third stage of the core Proton vehicle will ignite. Shutdown of the third stage will occur almost 10 minutes after liftoff, followed immediately by separation of the Block DM upper stage.

The Block DM will conduct three burns over the ensuing six-and-a-half hours to place Intelsat 903 into geostationary transfer orbit. Separation of the payload is expected around 6 hours, 43 minutes after launch.

On most commercial Proton launches, the Block DM fires twice to place a payload into the correct orbit. But because of the increased weight of Intelsat 903, a third burn has to be added shortly after third stage/Block DM separation to complete the job of inserting the upper stage and payload from a suborbital trajectory into a stable low Earth orbit 161 km (100 miles) high.

The later two upper stage burns will inject the payload into a geosynchronous transfer orbit with an apogee of 35,786 km (22,237 miles), perigee of 3,500 km (2,175 miles) and inclination of 25 degrees to the equator.

After separation from the Block DM upper stage, Intelsat 903 will use its own propulsion system to guide itself into a position above the equator in circular geosynchronous orbit at 34.5 degrees West, some 36,000 km (22,300 miles) above the Atlantic Ocean.

From that orbital slot, Intelsat 903 will use its compliment of Ku-band and C-band transponders to reach customers in Europe, North America, the Middle East, Africa, and South America. Services to be provided by the satellite during its 13-year mission include broadcasting, telephony, Internet, and corporate networking solutions.

Intelsat 903 will be the fourth satellite of the Intelsat 9 series to be launched into orbit. Intelsat 901, 902 and 904 were launched aboard European Ariane 4 rockets.

The Intelsat 9 satellites were built by Space Systems/Loral of Palo Alto, California, and is based on their FS1300 design. Intelsat 903 will weigh around 10,421 pounds at launch.

Watch this page for live updates during the countdown and ascent to orbit on Saturday.