Directory of U.S. Military Rockets and Missiles
Appendix 4: Undesignated Vehicles
Castor 4B
Copyright © 2007 Andreas Parsch

Orbital Sciences Castor 4B

The Castor 4B solid-propellant rocket stage can also be used stand-alone as a single-stage suborbital rocket. At the time of this writing, at least nine single-stage Castor 4B rockets have been launched, the first one in July 1996. The first military use of this rocket were two U.S. Army launches in August 2005 as part of the CMCM-1 (Critical Measurements and Countermeasures Program, Campaign 1) missile defense tests. The U.S. Navy has since used the Castor 4B as a target vehicle in three recent tests (between November 2005 and December 2006) of the Aegis ballistic missile defense system and the RIM-161 SM-3 missile. When used as target in missile defense tests, Orbital Sciences Corporation designates the Castor 4B rocket as the MRT (Medium-Range Target). The MRT can also be air-launched, using a cradle in the cargo space of a C-17 Globemaster III aircraft.

Photo: Orbital Sciences
Castor 4B MRT


On 15 September 1999, the U.S. Air Force launched a two-stage rocket consisting of a Castor 4B first stage and an M57A1 (3rd stage of surplus Minuteman I/II missiles) second stage. The rocket launched the ait-2 (atmospheric interceptor technology, Test Vehicle 2) mission, which conducted various experiments related to ballistic missile defense technology. The ait-2 vehicle was about 17.3 m (56 ft 10 in) long and weighed 14475 kg (31,912 lb) at liftoff.


Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!

Data for Castor 4B (dimensions and weight without payload):

Length8.8 m (29 ft)
Diameter102 cm (40 in)
Weight11500 kg (25400 lb)
Altitude> 300 km (190 miles)
PropulsionThiokol TX-859 Castor 4B solid-fueled rocket; 429 kN (96400 lb)

Main Sources

[1] Mark Wade: Encyclopedia Astronautica
[2] Jonathan McDowell: Launch Vehicles Database

Back to Directory of U.S. Military Rockets and Missiles, Appendix 4

Last Updated: 2 January 2007