[FLvoter]

So they could get through the Van Allen Belts 50 years ago, but not today? Ok

[chimera]

The Gemini (which had the initial traverses of the Van Allen regions) and Apollo flights were short-duration exposures. Today's missions are much longer duration. The ISS is orbited below the intense Van Allen zones for that reason. The Apollo lunar trajectories were also planned to avoid the intense regions.

Not a lot of people know, but the Van Allen "belts" are not continuous around the Earth. There are sections that are more intense than others, there are gaps and odd-shaped zones. Some of the regions are transient, and dissipate and re-form. The first penetration of the Van Allen regions by a manned spacecraft was Gemini 10, which made repeated traverses of the Southern Atlantic Magnetic Anomaly, which is a low-hanging swath of the inner Van Allen belts.