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Thor Delta with Explorer 10 Mar 25 1961.jpg
Thor-Delta prior to the launch of Explorer 10
Function Expendable launch system
Country of origin  United States
Launch history
Status Retired
Launch sites Cape Canaveral LC-17
Total launches 12
Successes 11
First flight 1960-05-13
Last flight 1962-09-18

The Thor-Delta, also known as Delta DM-19 or just Delta was an early American expendable launch system used for 12 orbital launches in the early 1960s. A derivative of the Thor-Able, it was a member of the Thor family of rockets, and the first member of the Delta family.[1]

The first stage was a Thor missile in the DM-19 configuration. The second stage was the Delta, which had been derived from the earlier Able stage. An Altair solid rocket motor was used as a third stage.[2]

The Thor-Delta was the first rocket to use the combination of a Thor missile and a Delta upper stage. This configuration was reused for a large number of later rockets, and a derivative, the Delta II, remained in service into 2011.

The Thor-Delta launched a number of significant payloads, including the first communications satellite, Echo 1A; the first British satellite, Ariel 1; and the first active direct-relay communications satellite, Telstar 1. All 12 launches occurred from Cape Canaveral Air Force Station Launch Complex 17. The launch of Telstar 1 used pad B, while all other launches were from pad A. All launches were successful except the maiden flight, which failed to place Echo 1 into orbit due a problem with the second stage.


  1. ^ Wade, Mark. "Delta". Encyclopedia Astronautica. Retrieved 2009-02-09. 
  2. ^ Krebs, Gunter. "Thor family". Gunter's Space Page. Retrieved 2009-02-09.