STS-41-D

Discovery's primary cargo consisted of three commercial communications satellites: SBS-D for Satellite Business Systems, Telstar 3C for Telesat of Canada, and Syncom IV-2, or Leasat-2, a Hughes-built satellite leased to the US Navy. Leasat-2 was the first large communications satellite designed specifically to be deployed from the Space Shuttle. All three satellites were deployed successfully and became operational.