Dec 9 1999
From The Space Library
The National Research Council (NRC) published a NASA-funded study, which found that NASA needed more safeguards to protect astronauts from potentially cancer-causing radiation during spacewalks they would make while building the International Space Station (ISS). The study recommended that NASA change flight rules, improve space-weather forecasting, and install a radiation-monitoring device outside the ISS. The NRC recommended the extra precautions because the station's assembly schedule, consisting of more than three dozen flights and 1,500 hours of spacewalks over four years, would coincide with the most active part of the 11-year solar cycle. Moreover, the report estimated a nearly 100 percent chance that at least two assembly missions would overlap with a serious solar storm and a 50 percent chance that five flights would overlap with such a storm. Additionally, the NRC predicted that a change in the station's planned orbit, which the Russian Space Agency had requested to accommodate Russian launches to help build and resupply the station, would increase the level of radiation exposure. George L. Siscoe, a Boston University physics professor and chairperson of the study, remarked that, although the radiation levels were not life threatening, they exceeded the 30-day and 60-day limits set to protect the skin and eyes. To safeguard crew from exposure to the increased risk of developing cancer later in life, countries participating in the ISS program would have to pay careful attention to flight schedules and crew rotation. Furthermore, the amount of radiation exposure sustained during ISS missions might affect an astronaut's chances of assignment to additional spacewalks and their selection for future missions.
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