This paper presents a general review and current support efforts in space radiation analysis and dosimetry at the NASA Johnson Space Center. Dating back to the Mercury program of the 1960's, radiation dosimeters have been worn by flight crews on every US space mission to measure and monitor the natural space radiation environment. Topics discussed include the space radiation environment, analytical spacecraft and anatomical modelling techniques, radiation dose programs, mission support functions and objectives, flight instrumentation, and measurements. Federal regulations for radiation protection and Space Shuttle astronaut dose limits are reviewed. The Shuttle mission operations support is discussed in detail, which includes pre-mission dose exposure computations, real-time Shuttle support activities, and post-flight analyses.