Sirius realizes its signal can be weak at times and that many listeners would appreciate a stronger, more consistent signal, as well as a wider range of services signal. Because of that, Sirius is considering launching a fourth satellite in 2008.
Sirius has a fourth satellite on the ground now as a backup in case one of the three in the sky suffers a catastrophic failure, so the next satellite would technically be the fifth. Launching that satellite would obviously be expensive (approximately $260M), but it would make the existing system more robust and cover many other areas. It would make them even more competitive with XM as well (it's worth noting XM is considering launching an additional satellite of their own). Additionally, Sirius can obviously survive on only three satellites, so if one fails in a constellation of four they could just rearrange them to the original positions.
If a fourth satellite is launched, the idea would be to have two satellites broadcasting and covering North America at any one time instead of only one. This next satellite is planned to use a more advanced signal broadcasting system to allow for great coverage and content capability. The fourth satellite is also planned to be geostationary, as opposed to the orbiting ones currently in the sky. This would provide far more consistent coverage and a stronger signal. Additionally, it would provide more consistent coverage to Central and possible South America as well as the Caribbean, so providing authorized service in those countries would be more realistic.
