Sirius FM-4 Communications Satellite

This satellite represents the first generation of space-based, commercial radio service developed by Sirius Radio, a U.S. company (now Sirius XM Radio). Designed in 1987 and initiating service in 2001, the Sirius satellite system consisted of three satellites that provided more than 150 digital music and audio channels to North America. Their inclined geosynchronous orbits were a distinctive design feature that enabled clear radio reception over the entire country.

This FM-4 spacecraft was built as a flight-ready backup for the system but never used. The round antenna on the side of the spacecraft transmits radio signals to the ground. The solar panels are stowed as if for launch. Fully opened in orbit, they would span more than 24 meters (78 feet).