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20 November 2009

Answer to Question #753 Submitted to "Ask the Experts"

Category: Environmental and Background Radiation — Space Flight

The following question was answered by an expert in the appropriate field:

Why were the astronauts, who traveled to the moon, not killed by exposure to radiation?

The radiation levels were too low to be lethal. Astronauts on Apollo missions were exposed to radiation from the Van Allen belts (trapped particles) and the galactic cosmic ray (GCR) background. There were no solar particle events of any significance during these missions; hence, there were no dose accumulations from them. Radiation exposures for the transits through the trapped belts were kept very low by transiting quickly through them. Since the Apollo mission lengths were only a week or two, there were also no significant accumulations of radiation dose from the GCR background. Thus doses were well below thresholds for any measurable radiation effects, including lethality. Average exposures to Apollo crews measured by onboard dosimetry were 4.1 mGy (0.41 rad) absorbed dose and 12 mSv (1.2 rem) dose equivalent for the mission duration.

Larry Townsend, PhD

Answer posted on 21 March 2001. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.