An artist's concept of a Sirius satellite in space. Photo: SS/L

Sirius Satellite Radio's first digital audio broadcasting spacecraft has successfully completed a series of examinations in orbit following its launch in June as the company's next craft is prepped for liftoff next month.

Sirius-1 was placed into a highly elliptical and highly inclined orbit by an International Launch Services (ILS) Proton rocket from the Baikonur Cosmodrome on June 30.

After spacecraft separation from the Proton's Block-DM upper stage, ground stations established contact with the satellite, and then the Space Systems/Loral-built spacecraft unfurled its power-generating solar arrays.

Sirius-1 arrived at its final orbit from the initial transfer orbit a few days after launch. The orbit features an apogee, or high point, of 47,112 kilometers, a perigee, or low point, of 24,456 kilometers and inclination of 63.3 degrees.

Over the weeks after launch, ground controllers with Sirius Satellite Radio took the first-of-a-kind spacecraft through a sequence of check-outs. Included were such things as tests of the S-band transponders that will broadcast Sirius' audio content, the attitude control and propulsion systems that will keep the satellite in the correct configuration and the electrical and data handling systems that will provide power and control the satellite once operational.

After analyzing the results from all tests, ground engineers declared the Sirius-1 satellite operational on July 31. However, the craft will not begin broadcasting its content until later in the year when the constellation's two other operational satellites are set to be launched.

Sirius-2 was recently shipped to Baikonur for launch on September 5 and Sirius-3 is scheduled to follow with liftoff in October. Both are to be hauled into nearly the same orbit as Sirius-1 and will be launched aboard ILS Proton rockets from Baikonur.

Sirius-4 will stay on the ground and will serve the role of a spare and would be flown only if one of the Sirius spacecraft was lost during launch or failed in orbit. The extra satellite was due for delivery in December but problems have pushed that back.

Sirius Satellite Radio will use its satellites to broadcast nearly 100 channels of radio and other audio programming to automobiles all across the continental United States and possibly beyond.

It has already struck deals with a variety of car and truck manufacturers to place receivers in car radios. The receivers would be activated for a $9.95 a month subscription fee. Featured channels include nearly 50 channels with different genres of music and 50 channels of variety programming including news, sports, and other informative channels.