The New York-based Sirius Satellite Radio Inc. announced that the launch of its Sirius 2 satellite on the Russian Proton rocket is scheduled for September 5. The launch window extends until September 15. The spacecraft left Space Systems/Loral manufacturing facility in California aboard a heavy transport plane on August 4, Sirius Radio representative Mindy Cramer told SPACE.com.

The four-stage Proton booster successfully delivered the original Sirius 1 satellite on June 30. After one month of in-orbit testing, the spacecraft was declared operational on July 31.

To provide complete coverage over the U.S., the entire Sirius network should include three operational satellites. Sirius 3 is scheduled for launch in October, also on a Proton rocket. When the satellite constellation is complete, Sirius plans to deliver 100 channels of digital-quality radio programming to motorists across the United States for a monthly subscription fee.

In the meantime, Sirius Satellite Radio said it expects a delay in the delivery of the Sirius 4 spacecraft, which would serve as a spare spacecraft for the network. Assembly problems were blamed for the delays.

Proton repairs its tarnished reputation

The Sirius 2 launch should follow another Proton mission currently scheduled for August 26. According to information from the Russian Aviation and Space Agency, Rosaviacosmos, the rocket will carry a Raduga spacecraft for military communications, also known as Globus. Sources familiar with the launch say that the mission could be delayed for several days to avoid a conflict with a silo-based launch of the Dnepr 1 booster, scheduled for August 25.

At least two other launches of the Proton rocket are planned for September. A Lockheed Martin GE-1A spacecraft is expected to lift off on the Proton in the mid September followed by a trio of Glonass navigation satellites for the Russian government.

The Proton booster has chalked up an unprecedented success rate in the past six months, following on the heels of a disastrous year. The booster returned to flight in February after two failures in 1999. Since then, Proton has scored eight flawless missions. Four of these Protons blasted off within a three-week period, between June 24 and July 12.