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Thor Delta B with TIROS 8 (Dec. 21 1963).gif
Delta B prior to the launch of TIROS-8
FunctionExpendable launch system
Country of originUnited States
Launch history
Launch sitesCape Canaveral LC-17
Total launches9
First flight13 December 1962
Last flight19 March 1964

The Delta B, or Thor-Delta B was an American expendable launch system used for nine orbital launches between 1962 and 1964. A derivative of the Thor-Delta, it was a member of the Delta family of rockets.

The first stage was a Thor missile in the DM-21 configuration, and the second stage was the AJ10-118, which was derived from the earlier Delta-A. An Altair solid rocket motor was used as a third stage.

All nine launches occurred from Cape Canaveral Air Force Station Launch Complex 17. Most of the launches carried communications satellites, including Syncom-1 and Syncom-2. Syncom-1 was intended to be the first satellite to be placed into a geosynchronous orbit, however the spacecraft malfunctioned prior to reaching this orbit. Syncom-2 subsequently became the first geosynchronous satellite, and was placed at 55° west of the Greenwich Meridian. The final launch failed due to third stage underperformance, all other launches were successful.


  • Wade, Mark. "Delta". Encyclopedia Astronautica. Archived from the original on 2008-07-24. Retrieved 2009-02-09.
  • Krebs, Gunter. "Thor family". Gunter's Space Page. Retrieved 2009-02-09.