U.S. satellite radio operators are facing real funding problems right now. Interspace recently reported that XM Satellite Radio might need an extra $600 million to reach cashflow breakeven. It now appears its main competitor, Sirius Satellite Radio, is also in trouble and that a bankruptcy filing cannot be dismissed out of hand. Sirius' recent financial performance has left many wondering whether the satellite radio operator has a future. In its recent results, the operator announced it had only 3,347 subscribers as of June 30.