How much radiation exposure do astronauts get in space?

Here are some numbers for various missions:

Mission.............Dose

Gemini 3                           23 millirads
Gemini 4                           46 millirads
Gemini 5                          176 millirads
Gemini 7                          164 millirads
Skylab                           2500 millirads
Apollo 11                         173 millirads
Shuttle (Average Skin Dose)      ~433 mrem/mission
Apollo 14 (Highest Skin Dose)   1,400 mrem / mission
Skylab 4 (Highest Skin Dose)   17,800 mrem/mission
Shuttle (Highest Skin Dose)     7,864 mrem/mission

For orbits at 250 - 300 km at 65 degree inclinations to the equator you get about 10 millirads/day. These numbers are from Volume II of the "Foundations of Space Biology and Medicine" NASA SP-374 published in 1975. Passes through the Van Allen radiation belts give you 10 - 20 rads/hour but most manned flights avoid them, and passages through them last about 10 - 20 minutes.

Here is a comparison to other common sources of radiation:

Airline Flight Crew                200 mrem/year
CT Scan (Chest)                    700 mrem/event
Barium Enema                       400 mrem/event
Houston Background                 100 mrem/year
Gas Cooking Range                  0.02 mrem/year
Dental Prosthesis                  0.02 mrem/year

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