The Apollo missions to the moon traveled at a record of roughly 40,000 km/h in transit to the moon, while the Van Allen radiation belt extends from 10,000 km to 60,000 km, with the most intensive portion of the belt at 20,000 km to 30,000 km. They spent at most an hour there and back inside the belt.
Additionally, the Van Allen belt consists mostly of electrons with energy levels ranging from 0.1 MeV to 10 MeV, meaning they cannot penetrate solid metal surfaces. Only satellites, which are exposed for years to the radiation, are at risk of severe malfunction, and even then, with little shielding they seldom fail.
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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.[29] The astronauts had low exposure in the Van Allen belts due to the short period of time spent flying through them.[30] 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.
In fact, the astronauts' overall exposure was dominated by solar particles once outside Earth's magnetic field. The total radiation received by the astronauts varied from mission to mission but was measured to be between 0.16 and 1.14 rads (1.6 and 11.4 mGy), much less than the standard of 5 rads (50 mSv) per year set by the United States Atomic Energy Commission for people who work with radioactivity.[29]