From the earliest uses of active and passive radiation instrumentation on the Mercury-Atlas missions (MA-8 and MA-9) to our current planning for the space station and exploration missions, space radiation measurement systems have undergone a myriad of significant changes. Systems to measure the radiation environment for the Mercury, Gemini, Apollo, Skylab, and Shuttle are described and discussed. Measurements from instrumentation used on these programs have shown that the space radiation environment, both in low-Earth orbit and in free space, is both temporally and spatially dynamic - resulting in changes in analytical models, measurement philosophies and systems, and mission planning activities. Three decades of experiences in the prediction and measurement of space radiation on manned spacecraft are examined, with emphasis on current and future radiation measurement systems, radiation environment predictive capabilities, and exposure standards and uncertainties. Expected radiation environments of a Lunar Base and a typical Mars mission are discussed, as are descriptions of the radiation environmental monitoring systems that are proposed to support those missions.