The Delta G, or Thor-Delta G was an American expendable launch system used to launch two biological research satellites in 1966 and 1967. It was a member of the Delta family of rockets.The Delta G was a two-stage derivative of the Delta E. The first stage was a Thor missile in the DSV-2C configuration, and the second stage was a Delta E. Three Castor-1 solid rocket boosters were clustered around the first stage.