Only NASA knows why it faked the moon landings, but many have surmised that the radiation of the Van Allen Belts would have killed astronauts in a relatively thin-walled spacecraft. It is estimated that a ship would need walls several feet thick to adequately shield the crew from radiation. Unfortunately, however, a ship with several feet thick, radiation-proof walls would have been too heavy to get off the launchpad. D’oh!
The Van Allen Belts are not all bad though. They protect us from the Sun’s lethal radiation and a litany of other cosmic radiation sources while making the Earth uniquely livable for mankind.
A recent article about the Van Allen Belts: