Radiation Exposure to Astronauts During EVAs

During EVAs astronauts can receive significant additional radiation exposure to the skin and eyes due to the minimal shielding provided by the EMU. Occupational health and safety standards for astronaut radiation exposure exist, but there are no unique EVA rules nor requirements for the shielding provided by the EMU. The ALARA concept requires “reasonable” actions be taken to minimize additional exposure. This is most effectively accomplished by avoiding EVAs in orbital regions where additional exposure occurs. Measurements during the Shuttle program do not properly reflect actual EVA exposures because of the poor location of the dosimeter inside the EMU. A measurement program is underway to determine the shielding provided by the EMU, as well as the optimal location for accurate dosimetric measurements.