Space radiation dosimetry presents one of the greatest challenges in the field of radiation safety. In the present paper the dosimetric data collected over the last 20 years of radiation field measurement on near-Earth orbits are presented. The measurements were carried out aboard "Cosmos" spacecrafts (1979-1989), "Mir" station (1988 and 1991), as well as on board the ISS (2002). For determination of important characteristics of cosmic rays (particle fluxes, LET and fast neutron spectra, equivalent doses and heavy ion fluxes) a nuclear emulsion has been used as a controllable threshold detector. An integral LET spectrum was measured in the range of 0.5-3.5 × 10 3 keV/μm. The energy spectra of fast neutrons with E = 1-15 MeV have been also studied and induced equivalent doses calculated.