- Family: Thor-Ablestar
- Length: 29 m
- Diameter: 1.44 m
- Launch Mass: 51 T
- Low Earth Orbit Capacity: 150 kg
The Thor DM-21 Ablestar was manufactured by United States Air Force with the first launch on 1960-04-13. Thor DM-21 Ablestar has 13 successful launches and 6 failed launches with a total of 19 launches. The Thor-Ablestar, or Thor Able-Star, also known as Thor-Epsilon was an early American expendable launch system consisting of a PGM-17 Thor missile, with an Ablestar upper stage. It was a member of the Thor family of rockets, and was derived from the Thor-Able.