If you want to actually learn how they solved the issue of traveling through the Van Allen belts you could read this: https://www.forbes.com/sites/jillianscudder/2017/06/16/astroquizzical-van-allen-belts-barrier-spaceflight/#79443bb36f8d

The difficulty of the belts is the radiation given to the astronauts traveling through, so they aimed well to minimize the damage. They only received minor radiation.

If you want to learn some useful innovations created through NASA research there are countless pages on the subject, such as this one: https://www.jpl.nasa.gov/infographics/infographic.view.php?id=11358