Satellite Data System

The Satellite Data System (SDS) is a system of United States military communications satellites. At least three generations have been used: SDS-1 from 1976 to 1987; SDS-2 from 1989 to 1996; SDS-3 from 1998 to the present. It is believed that these satellites were known by the code name Quasar.^[1] The first generation was named simply 'SDS', the second generation was named 'Quasar' and the third generation each had their own designations.^[2]