XM 3, 4 (XM Rhythm, Blues)

XM 4 [Boeing BSS]

Hughes Space and Communications International, Inc., now Boeing Satellite Systems, Inc., and XM Satellite Radio Inc. (XMTM) signed a contract to deliver ewo more satellites designed to provide state-of-the-art digital audio radio programming directly to cars, homes and portable radios coast to coast. The XM-3 and XM-4 satellites are redsigned versions of the earlier XM-1 and 2 satellites without the design flaw of the solar arrays.

These satellites are among the most powerful ordered to date. Each is designed to provide 18 kilowatts of total power at beginning of life. To generate such high power, the two solar wings employ five panels each of high-efficiency, dual-junction gallium arsenide solar cells. To provide 15 years' service, the BSS-702 carries the flight-proven xenon ion propulsion system (XIPS) for all on-orbit maneuvering. Alcatel Espace of Toulouse, France, will provide the high-power, S-band, Digital Audio Radio Service payload.

XM 3 has redesigned solar arrays, as the original concentrator arrays have a fogging problem reducing the performance. XM 4 has also a back-up bi-propellant system for the XIPS thrusters.

The satllites will be replaced in 2019 and 2020 by the SXM 7 and 8 satellites.