Prognoz, also known as SO (Solar Object, first three satellites), SO-M (SO-modified, next seven satellites) and SO-M2 (last two satellites, also known as Interball) was a Soviet scientific research satellite programme. Twelve Prognoz satellites were launched between 14 April 1972 and 29 August 1996, by Molniya-M carrier rockets. The satellites were placed in High Earth orbits. First ten Prognoz spacescrafts were launched from Site 31/6 at the Baikonur Cosmodrome and last two from Site 43/3 at the Plesetsk Cosmodrome.^[1][2][3]

The satellites were primarily used for Solar research, however the later satellites were used for other research, including research into the Big Bang theory, and Earth's magnetosphere.^[4] The tenth satellite was used as part of the Interkosmos programme.

• Interkosmos