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A new radiation measurement system for the realtime measurement of absorbed depth dose and dose-equivalent from space radiation within a phantom is being developed. The head and torso of the “average male” phantom (height 175 cm, weight, 73.5 kg) will be instrumented with active and passive radiation dosimeters and flown as an experiment on a Shuttle mission in 1996. The unique dosimetry system, which utilizes both pulse height analysis and internal data storage, is described. The active systems will be supported with a large number of passive dosimeters (lithium fluoride thermoluminescent detectors and CR-39 plastic nuclear track detectors) distributed throughout the phantom. Previous earlier measurements of space radiation dose distribution within a phantom head are reviewed. Unfortunately, results from both passive and active radiation measurement systems on the head-torso phantom experiment are not yet available.

Longer on-orbit crew stay times anticipated during the construction and habitation of the International Space Station (ISS) will necessarily require the development of a new generation of radiation measurement instrumentation. The planned orbit of 51.6° inclination at 470 km will result in significantly higher daily crew exposures than experienced during the bulk of previous U.S. space missions. In addition, the National Commission for Radiation Protection and Measurement (NCRP) is revising the guidelines for crew radiation exposures. It is anticipated that the new guidelines will call for dose and dose-equivalent limits that are substantially less than those currently used in the space program. The cornerstone elements of the planned radiation measurement instrumentation for the ISS are a tissue-equivalent proportional counter (TEPC) and a directional charged particle spectrometer. These active systems will be supported by NASA's standard passive (thermoluminescent) dosimetry system.

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.

Passive dosimeters have been extensively used to measure space radiation exposures to crewmembers for over three decades. Although a significant evolution in materials, processes, readout, and analysis techniques for these sensors has been witnessed during this period, these simple devices remain the backbone of the current operational dosimetry program for the Space Shuttle. Indeed, the utilization of passive dosimeters is also planned for the space station as well as advanced manned exploration programs, i.e., Lunar Base and Mars missions. Sensor materials and types have included thermoluminescent dosimeters, radiation-sensitive films and emulsions, and plastic nuclear track detectors. Early, transitional, and current passive dosimeter materials, systems, and techniques to measure space radiation are described and discussed, with major emphasis on the development of thermoluminescent dosimetry (TLD) techniques.