FURTHER ANALYSIS OF THE SPACE SHUTTLE EFFECTS ON THE ISS SAA DOSES
G. De Angelis;J. Semkovat;B. Tomovt;Pl. Dimitrovt;Yu. Matviichukt;N. Bankovt;G. Reitz;G. Horneck;D.-P Häder (2011). "FURTHER ANALYSIS OF THE SPACE SHUTTLE EFFECTS ON THE ISS SAA DOSES." International Astronautical Federation AC-11,A1,4,2,x9918
The data from the R3DE instrument of ESA’s EXPOSE-E mission outside the ISS at the European Technological Expose Facility (EuTEF) on the ESA Columbus module shows that the docking of the Space Shuttle with the International Space Station (ISS) decreased the South-Atlantic Anomaly (SAA) maxima dose rates from about 1500 Gy h-1 down to 600-700 Gy h-1 or by factor of 2. The dose rate data at the same time from another Bulgarian built instrument (R3DR) of the EXPOSE-R mission outside the Russian “Zvezda” module showed that: 1) before the Space Shuttle docking, the SAA dose rates measured with R3DR were higher (2500 Gy h-1) than the R3DE data; 2) The relative decrease of the SAA dose rates after the shuttle docking was only by a factor of 1.25. These differences are explained by the smaller shielding of R3DR from the body of ISS and by the larger distance of it from the body of Space Shuttle. Very similar data, but with smaller dose rates were obtained with a third Bulgarian built instrument (Liulin-5) inside Russian “Pirs” module. The analysis of the ascending/descending SAA dose rate maxima of the three instruments shows that the effect can be simply explained by the additional shielding against the 30 to 150 MeV protons of the SAA, provided by the 78 tons Shuttle to the instruments and by changing of the ISS 3D mass distribution when the ISS rotates.