2:50 PM -- Satellite radio is still soaring.

Some earlier projections may have been too conservative. It now looks as if the U.S. will easily have 17.1 million satellite radio subscribers in 18 months.

Sirius Satellite Radio (Nasdaq: SIRI), for one, is growing like a weed. The company has 4 million subs now. By the growth rate the company is assuming to make its 2006 numbers -- roughly 310 new subs an hour -- Sirius will add another 4 million subscribers in just 18 months.

Should we assume a much slower growth rate? We could. The company added subscribers at a rate of about 243 an hour between July 2004 and March 2006. Even at that slower rate, they're clocking in more than 1 million new subs every 6 months. They'll have about 3.1 million new subs in 18 months, giving them 7.1 million.

What's XM Satellite Radio (Nasdaq: XMSR) doing? It grew at a rate of about 284 new subs an hour between June 2004 and April 2006. So it will add somewhere close to 3.6 new subs in the next 18 months, giving it 10.1 million subs overall.

What will happen next at Sirius and XM? Here are my predictions:

— Phil Harvey, News Editor, Light Reading