BY JUSTIN RAY

September 5, 2000 -- Follow the countdown and launch of the Proton rocket launching the Sirius 2 spacecraft for Sirius Satellite Radio. Reload this page for the very latest on the mission.

1230 GMT (8:30 a.m. EDT)

SPACECRAFT SEPARATION CONFIRMED! The second Sirius Satellite Radio spacecraft has been successfully launched into orbit today by a Russian Proton rocket. International Launch Services, which oversaw the mission, confirms the Block DM performed two scheduled firings and then deployed the Sirius 2 satellite into the correct highly elliptical, highly inclined orbit around Earth.

Read our full story for a complete recap of the launch.

1030 GMT (6:30 a.m. EDT)

Watch a QuickTime video clip of today's launch (434k file).

0958 GMT (5:58 a.m. EDT)

T+plus 14 minutes. The Block DM upper stage has entered a coast period in its parking orbit around Earth with the attached Sirius 2 satellite.

At T+plus 43 minutes, 50 seconds the first of two firings by the Block DM is scheduled to boost Sirius 2 to toward its intended elliptical orbit around Earth. The second firing is planned at T+plus 2 hours, 3 minutes and 17 seconds.

Separation of Sirius 2 to complete this launch is expected at T+plus 2 hours, 25 minutes and 10 seconds, or 1209 GMT (8:09 a.m. EDT).

We will pause our coverage at this time. Check back for confirmation of spacecraft separation later this morning.

0954 GMT (5:54 a.m. EDT)

T+plus 10 minutes, 30 seconds. And now confirmation the Proton rocket's third stage has dropped away, leaving the Block DM upper stage with Sirius 2 spacecraft in a parking orbit around Earth.

0954 GMT (5:54 a.m. EDT)

T+plus 10 minutes. Third stage engine cutoff confirmed.

0952 GMT (5:52 a.m. EDT)

T+plus 8 minutes, 30 seconds. The rocket has now leveled out in its altitude but continues to gain speed. Atltitude is 181 km, downrange distance 1,498 km.

0951 GMT (5:51 a.m. EDT)

T+plus 7 minutes, 30 seconds. Altitude is 181 km, downrange distance 1129 km.

0951 GMT (5:51 a.m. EDT)

T+plus 7 minutes. The Proton rocket continues right along the projected flight path. No problems have been reported during the launch so far.

0950 GMT (5:50 a.m. EDT)

T+plus 6 minutes. The second stage has shut down and separated. The third stage engine ignition confirmed. Also the payload fairing has been jettisoned.

0949 GMT (5:49 a.m. EDT)

T+plus 5 minutes. Second stage engines still firing properly with a half-minute left in their burn.

0948 GMT (5:48 a.m. EDT)

T+plus 4 minutes. Altitude is 105 km, downrange distance 259 km.

0947 GMT (5:47 a.m. EDT)

T+plus 3 minutes. Second stage engine chamber pressures are normal. Altitude passing 68 km, downrange distance 109 km.

0946 GMT (5:46 a.m. EDT)

T+plus 2 minutes, 30 seconds. The second stage engines have ignited and the spent first stage has dropped away.

0945 GMT (5:45 a.m. EDT)

T+plus 90 seconds. Pitch, yaw and roll of the rocket normal. Altitude 32 km, downrange distance 30 km.

0945 GMT (5:45 a.m. EDT)

T+plus 60 seconds. A spectacular launch of the Proton rocket. Vehicle is stable and engines performing as expected.

0944 GMT (5:44 a.m. EDT)

T+plus 30 seconds. Roll maneuver has started to place the rocket on the proper flight azimuth for Sirius 2. The rocket's six first stage RD-253 engines are up and running normally.

0943:58 GMT (5:43:58 a.m. EDT)

LIFTOFF! Liftoff of the Proton rocket and the second spacecraft for Sirius Satellite Radio's orbiting broadcast system.

0943 GMT (5:43 a.m. EDT)

T-minus 1 minute. 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.

0942 GMT (5:42 a.m. EDT)

T-minus 2 minutes and counting. The Sirius 2 spacecraft, Proton rocket and Block DM upper stage have been declared ready for launch.

0940 GMT (5:40 a.m. EDT)

T-minus 4 minutes and counting.

0938 GMT (5:38 a.m. EDT)

T-minus 6 minutes and counting. The Proton rocket weighs 1,719,606 pounds as it sits on the launch pad. The rocket was fully fueled over the past six hours. The Sirius 2 spacecraft accounts for 8,377 pounds of the weight. At launch the Proton's six first stage engines will fire together to lift the massive rocket skyward into the afternoon skies at Baikonur.

0934 GMT (5:34 a.m. EDT)

Now inside the final 10 minutes to liftoff of the International Launch Services Proton rocket. This will be ILS' 16th Proton mission dating back to 1996. All but one of the previous launches have been successful.

Overall this will be 280th Proton rocket extending back to 1965, and will be the 10th of 2000.

0924 GMT (5:24 a.m. EDT)

T-minus 20 minutes and counting. No problems to report as the countdown continues towards an on-time liftoff today of Sirius 2.

The Proton rocket's first three stages that make up the core vehicle will complete their mission during the first 9 minutes, 49 seconds of the launch.

The Proton third stage will deploy the Block DM upper stage and attached Sirius 1 spacecraft in 92 nautical mile circular parking orbit inclined 64.8 degrees to the Earth's equator. The Block DM will conduct the first of two firings at T+plus 43 minutes, 50 seconds to begin the journey into the desired orbit for Sirius 2. The burn will last about six minutes.

A second burn is planned at T+plus 2 hours, 3 minutes, 17 seconds to completed the powered phase of today's launch. The second Block DM firing is expected to last just under two minutes.

Separation of Sirius 2 from the Block DM will occur 2 hours, 25 minutes, 10 seconds after liftoff.

0914 GMT (5:14 a.m. EDT)

T-minus 30 minutes and counting. All activities are on schedule at Complex 81's pad 23 at the Baikonur Cosmodrome for liftoff of the Proton rocket today at 0943:58 GMT.

The Sirius 2 spacecraft being launched will be the second in Sirius Satellite Radio's constellation. It will operate in a egg-shaped orbit ranging from 14,900 miles at the low point to 29,200 miles at the high end, inclined 63.4 degrees.

The craft will join Sirius 1 launched in June, and Sirius 3 should follow suit later this fall to provide 100 channels of digital radio to subcribers across the United States.

Here is a look at the orbital parameters of the Sirius constellation:

Inclination 63.4 deg, ±0.5 deg
Eccentricity 0.2684 ±0.005
Orbit Period ~24 Hours
Relative Phasing 8.0 Hr ±10 minutes
Semi-Major Axis 42,164 km
Pedigree Radius 24,469 km
Apogee Radius 47,102 km
RAAN 45.0 deg, 165.0 deg, 285.0 deg
Argument of Perigee 270.0 deg ±0.5 deg
Apogee Longitude 96.0 deg W ±0.5 deg
Mean Anomaly Y deg Y-120.0 deg, Y-290.0 deg

0909 GMT (5:09 a.m. EDT)

T-minus 35 minutes and counting. Officials at the Baikonur Cosmodrome launch site report weather conditions are well within acceptable limits for the Proton's liftoff today. The temperature is currently 32 degrees C, or 95 degrees F, and winds are from the west at 5 to 8 meters per second.

0904 GMT (5:04 a.m. EDT)

T-minus 40 minutes and counting. The launch team has just a 12-second window in which to get the Proton rocket off the ground today. This timing is dictated by the Sirius 2 satellite payload's required placement into Earth orbit. The window opens at 0943:58 GMT and extends to 0944:10 GMT. It should be noted, however, that rarely does a Proton ever miss its appointed launch time.

0900 GMT (5:00 a.m. EDT)

The rocket is fueled, the spacecraft is being readied and the weather is acceptable for today's Earth-shaking blastoff of the mighty Russian Proton rocket from the Baikonur Cosmodrome in Kazakhstan. Liftoff is just 44 minutes away and there are no problems to report.

It is now 3 p.m. local time at Baikonur and 5 a.m. here on the East Coast of the United States. Although it is quite early for Americans, the daytime launch from the remote steppes of Central Asia should provide a spectacular view of the Proton streaking to space on the power of its six engines at the base of the first stage.

The countdown is under computer sequencer control through the remaining time until liftoff. Also, the launch team has provided the final updates to the rocket's guidance computer for today's mission.

0820 GMT (4:20 a.m. EDT)

It is launch day for the Proton rocket carrying the Sirius 2 digital radio broadcasting satellite. Live countdown updates and launch coverage will begin at the top of the hour.

MONDAY, SEPTEMBER 4, 2000

Sirius Satellite Radio, the New York City-based pioneer of digital radio via orbiting spacecraft, hopes to have its second of three primary satellites delivered aloft on Tuesday by a Russian-made Proton rocket.

Liftoff is scheduled for precisely 0943:58 GMT (5:43:58 a.m. EDT) from pad 23 of Launch Complex 81 at Baikonur Cosmodrome in Kazakhstan. The mission is managed by International Launch Services -- the joint venture between Lockheed Martin, Khrunchiev and Energia formed in 1995 to market the American Atlas and Russian Proton rockets. This will be the 16th Proton flight for ILS and third of 2000.

The three-stage Proton core vehicle and Block DM upper stage will need just shy of 2 1/2 hours to place the Sirius 2 satellite into a highly inclined, highly elliptical orbit around Earth. The craft will later manuever itself into formation with Sirius 1 launched on June 30, and then await the arrival of Sirius 3 this fall before the trio begin commercial radio broadcasting services by year's end.

Sirius Satellite Radio plans to be the first such company to market digital audio programming directly to autmobiles outfitted with special receiving antennas to pick up 100 channels of music, news, sports and entertainment through its network of three spacecraft.

The Sirius service will be available to customers in across the continental United States for a monthly subscription of $9.95.

"The promise of satellite radio is seamless, coast-to-coast coverage across the continental United States, a system that will permit our customers to drive from New York to California and from Chicago to New Orleans and never lose the Sirius satellite signal," said Ira Bahr, Sirius' senior vice president for marketing.

The satellites are being strategically placed in egg-shaped orbits looping from 14,900 miles at the low point to 29,200 miles at the high end, inclined 63.4 degrees to either side of the equator. The satellites will be spread apart such that two are always in view of the U.S., and as one sets another one rises.

The orbit is unusual for a commercial communications satellites. Normally such satellites fly in circular geostationary orbit 22,300 miles high where the craft can match the Earth's spin and "park" over one spot of the globe.

But since Sirius aims to reach cars driving on the road with man-made and natural obstacles blocking the view to satellites flying above the equator, the special orbit plan was needed.

"What we discovered after testing that the geostationary satellite configuration does not provide high enough angles of elevation to deliver the seamlessness of coverage that we felt was really critical," Bahr said.

Potential roadblocks are anything from a 2-story building to tractor-trailers driving next to you.

"The result (of the Sirius orbit) is that we always have a satellite which is in excess of 60 degrees angle of elevation."

Spaceflight Now will provide continuous live status reports during the final countdown and launch on Tuesday here on this page. In addition, we will offer a live QuickTime streaming video broadcast starting at 0900 GMT (5 a.m. EDT).