The Delta 5000 series was an American expendable launch system which was used to conduct an orbital launch in 1989. It was a member of the Delta family of rockets. Although several variants were put forward, only the Delta 5920 was launched. The designation used a four digit numerical code to store information on the configuration of the rocket. It was built from a combination of spare parts left over from earlier Delta rockets, which were being retired, and parts from the Delta II 6000-series, which was just entering service.
The first stage was the RS-27 powered Extended Long Tank Thor, flown on several earlier Delta rockets. Nine Castor-4Asolid rocket boosters were attached to increase thrust at lift-off, replacing the less powerful Castor-4 boosters used on the 3000 series. The Delta-K was used as a second stage. In the configuration that was launched, no third stage was flown.