An artist's concept of XM radio broadcasting spacecraft built by the new Boeing Satellite Systems.

XM Satellite Radio reports that its first spacecraft is performing well during initial testing and checkout in orbit while preparations continue for the launch of the sister digital radio broadcasting craft next month.

Since its launch on March 18 aboard a Sea Launch Zenit 3SL rocket, XM-2, or "Rock," has successfully completed a large chunk of its critical testing phase.

"The satellite's communications antennas and solar wings have now been successfully deployed, following a successful series of five firings of the satellite's on-board liquid apogee engine," said Randy Brinkley, president of Boeing Satellite Systems, the manufacturer of both XM spacecraft. "The satellite's state of health continues to be excellent."

XM-2 was originally supposed to launch after XM-1, called "Roll," but a minor payload glitch in a January 8 launch attempt cropped up just seconds before liftoff. The RD-171 engine had already begun its pre-ignition procedures at this time, forcing officials to sail back to California to change out the powerplant.

In February, the decision was made to launch XM-2 first, and to postpone XM-1 until May with a fresh Zenit rocket. Part of the planning behind this decision was to keep XM-2's processing flow on schedule for launch in March. Also, this kept the planned XM service rollout date on target for this summer.

"We have a bird in the air and another bird ready to fly," said Hugh Panero, XM President and CEO. "XM is on schedule for its summer rollout. XM-ready radios are on retail shelves, final chipsets are with our radio manufacturers and our broadcast studio is creating content."

"Roll" is set for launch now on May 7 from the Odyssey launch platform in the Pacific Ocean.

"Rock" and "Roll" are both based upon Boeing's 702-satellite model design. They have two 16.4-ft. folding deployable S-band transmit reflectors and one X-band global receive antenna. The satellites span 132.5 feet in length and 46.6 feet in width with antennas fully deployed, and have a total spacecraft power of 18 kilowatts. The satellites carry digital audio radio payloads that each feature two active transponders generating approximately 3,000 watts of radio frequency power, making these the most powerful commercial transponders ever built.

"Rock" will operate in a geostationary orbit at 115 degrees west longitude with a mass of 6,505 pounds (2,950 kg) in orbit. "Roll" will operate at 85 degrees west longitude.

XM Satellite Radio will provide digital-quality audio broadcasts to cars, trucks and homes across America for the price of $9.95 per month.