The first of two satellites designed to broadcast digital audio over North America is set for an ocean launch this week. The two satellites, named Rock and Roll by XM Satellite Radio Inc., will offer 100 channels of fee-based digital programming to owners of satellite radios, mostly in new cars. Roll will launch from a floating platform near the equator into low orbit before boosting itself to geosynchronous position 22,236 miles up. When the satellites are in place, the owner of a digital radio could listen to a favorite station anywhere in the US. An accompanying article from Forbes expresses skepticism concerning the ability of satellite digital radio to make a profit.