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. 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.

Versions

Flown versions

Castor 1

Castor 2

Castor 4

Castor 30

Castor 120

Proposed versions - based on Space Shuttle SRB

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

Castor 300

Castor 600

Castor 1200