Abstract : Numbering about 3,450 officers during 2001, the 13S career field (space and missile operations) in 1994 merged the separate space and missile career fields. While the nation's intercontinental ballistic missile force has shrunk substantially during the service of many of today 's officers, the space-based systems for navigation, surveillance, warning, and communication have become more numerous. Although missile jobs remain more numerous for junior officers, increasingly more space-oriented jobs are becoming available for midand senior-level officers. While missile operations generally follow detailed and rigid standard operating and safety procedures, space system operations are more varied and flexible, although they have also grown more standardized and routinized. Finally, civilians (often contractor personnel) play significant roles for space systems but not in missile operations. AFSPC has issued inconsistent career guidance to 13S officers, once recommending experience across all five categories of operations and systems missile combat crew, satellite command and control, launch (also called spacelift), surveillance, and warning and later recommending only a major and a minor area of mission expertise. AFSPC leaders have wondered whether the career field is so diverse and unbalanced that it may not be sustainable. In 2001, the Rumsfeld Space Commission decried a lack of experience among space officers; raised the possibility of creating a separate space corps; called for intensified, career-long education and training for space professionals; and mandated specific criteria . . . for the selection, training, qualification and assignment of space personnel who will design, develop, acquire and assess military space systems.