Castor (rocket stage)

Castor is the name of a class of American solid rocket motors Thiokol.


The development goes back to 1959, as an inexpensive rocket stages for the Scout rocket as a second stage or the Little Joe -1 were required. The rocket is based on the military Sergeant missile, from which the original versions of Pollux and Castor were developed. The Pollux engine was not developed further, while the Castor motor learned as Castor - II, a further increase in performance. The Castor -IV variant is a new development of the seventies, which is significantly larger and more powerful than their predecessors.

Your biggest use got this solid rocket booster as for the delta, where supported the first phase starting in almost every start three to nine of these engines. Also Castor rockets were to increase the performance of the Atlas IIAS and used to drive a series of sounding rockets. In addition, they found seven times bundled with the Conestoga rocket use.

Important stages of development were:

  • Pollux
  • Castor I: use 1960-1972 about 365 pieces
  • Castor II: Application 1960-1994 approximately 1045 pieces; Licensed production in Japan for H -I
  • Castor IV: ( A versions without control, B with thrust vector control )
  • Castor IVA -XL (extended IVA with 30% more thrust)


Specific performance data are presented from different sources with slight differences (eg due to other conversions, etc.)

Castor IVA were first used in 1989 at a Delta rocket and since December 15, 1993 as an Atlas IIAS booster. Different panels and nozzle shapes serve to adapt to the particular application or as a booster stage.

Castor 120

The much larger version of Castor 120, which was launched as a first stage of the Athena rocket on 22 August 1997 for the first time, is developmentally unrelated to the older Castor rocket motors, but based on the first stage of the Peacekeeper ICBM. The Castor -120 rocket motor also serves as the first stage of the Taurus rocket.

Castor 30

The Castor -30- Booster is a highly condensed castor -120 booster. The number 30 stands for 30,000 pounds of fuel. Castor 30 is used as a second stage in the Antares rocket use. The Castor -30 Booster as a second stage of Athena 1c and 2c as the third stage of Athena use

Took place on 9 December 2009 for the first time, a static firing test with a castor -30 booster.