Castor (rocket stage)

Castor is a family of solid-fuel rocket stages and boosters built by Thiokol (now Northrop Grumman) and used on a variety of launch vehicles.

[1] They were initially developed as the second-stage motor of the Scout rocket.

The design was based on the MGM-29 Sergeant, a surface-to-surface missile developed for the United States Army at the Jet Propulsion Laboratory.

[2][3] Instead of using a D6AC steel case and PBAN binder like the Space Shuttle SRB, these will use the technology derived from the GEM motors which have carbon composite cases and HTPB binder.

[11] The carbon composite design eliminates the factory joint common on all Space Shuttle SRBs.

Diagram showing the use of a Castor as the second stage of a Scout-B vehicle
Castor 30 rocket motor being ground-tested
A Castor 120 that was used as Stage 0 of a Taurus XL rocket for the OCO launch