First - SAA, a lower tip of the belts with a very very light radiation of about 2,5 rem/h at 445km:
However this "light radiation dip" kill Hubble electronic, so they end up shutting Hubble off when it pass thru this region of increased radioactivity. If they try picture something during the SAA transit, then even when the shutter is closed (!) and the picture should be pitch black then, it looks like that:
(book The Hubble Wars, page 75)
So, this is how 2.5 rems/h radioactivity looks like!
Now imagine the hell, that it in the belts... add the fact, that aluminium is actually worsening the problem because of secondary particle fragmentation and you get the cooked astroNOT long before the CSM exit the belts
Ships with crew can't fly there w/o special shielding: "Flights of manned spacecraft in the central zone of the ERB are impossible without special shielding.".
But no rocket can carry up such shielding. Some astrophysicist suggest that the radiation exposure is "manageble" when there is at least 2 meters of water shielding. Earth give us the equivalent of 10 meters... and if you want go anywhere near the Sun, the requirments grow exponentially.
Why do you think we can't get even to the damn Moon?!
Read the rest of the story.
The Apollo missions marked the first event where humans traveled through the Van Allen belts, which was one of several radiation hazards known by mission planners. The astronauts had low exposure in the Van Allen belts due to the short period of time spent flying through them. The command module's inner structure was an aluminum "sandwich" consisting of a welded aluminium inner skin, a thermally bonded honeycomb core, and a thin aluminium "face sheet". The steel honeycomb core and outer face sheets were thermally bonded to the inner skin.
Radiation was not an operational problem during the Apollo Program. Doses received by the crewmen of Apollo missions 7 through 17 were small because no major solar-particle events occurred during those missions. One small event was detected by a radiation sensor outside the Apollo 12 spacecraft, but no increase in radiation dose to the crewmen inside the spacecraft was detected. Solar-particle releases are random events, and it is possible that flares, with the accompanying energetic nuclear particles, might hinder future flights beyond the magnetosphere of the Earth.
Radiation protection for the Apollo Program was focused on both the peculiarities of the natural space radiation environment and the increased prevalence of manmade radiation sources on the ground and onboard the spacecraft. Radiation-exposure risks to crewmen were assessed and balanced against mission gain to determine mission constraints. Operational radiation evaluation required specially designed radiation-detection systems onboard the spacecraft in addition to the use of satellite data, solar observatory support, and other liaison. Control and management of radioactive sources and radiation-generating equipment was important in minimizing radiation exposure of ground-support personnel, researchers, and the Apollo flight and backup crewmen.