Active dosimetry on recent space flights.

Abstract

The radiation exposure inside the spacecraft in low earth orbit was investigated with a telescope based on two silicon planar detectors during three NASA shuttle-to-MIR missions (inclination 51.6 deg, altitude about 380 km). Count and dose rate profiles were measured, as well as separate linear energy transfer (LET) spectra, for the galactic cosmic rays (GCR) and the trapped radiation encountered in the South Atlantic Anomaly (SAA). Effective quality factors are deduced from the converted LET spectra (in water) in the range 0.1-120 keV micrometer-1 according to ICRP 60. Measured mission averaged dose rates in silicon are in the range 98-108 microGy d-1 and 137-178 microGy d-1 for the GCR and SAA contributions, respectively. The deduced effective quality factors are 2.95-3.29 (GCR) and 1.18-1.25 (SAA), resulting in mission averaged dose equivalent rates of 631-716 microSv d-1 for the comparable three missions.