spacetoday.net: ISS radiation shielding not as good as hoped

Posted: Thu, Oct 24, 2002, 9:04 AM ET (1304 GMT)
ISS illustration (NASA)

Upgraded radiation shielding on the International Space Station is not working as well as expected, New Scientist reported Wednesday. According to the report, radiation levels within the station are about one millisievert per day, about the same amount of radiation one would get on the ground from natural sources in one year. Those levels are within a few percent of those measured on Mir despite the use of new shielding on the station designed to lower radiation levels. The primary source of the radiation is the collision of cosmic rays with aluminum atoms in the hull, creating a shower of particles. The new shielding uses polyethylene, whose lighter atomic nuclei were designed to reduce the amount of secondary particles released in collisions. Experts told New Scientist that a whole new type of shielding may be required for future missions beyond the Earth's protective magnetosphere, which shields the ISS of high-speed particles from the Sun.