SpaceX is about to send four people on a wild — and risky — mission into the radiation belts. Here's what to know

When a billionaire self-funded a mission to orbit Earth in 2021, the project was billed as a childhood cancer fundraiser and marked an impressive entry into private space tourism. A four-person crew with no prior spaceflight experience spent three days orbiting Earth in a SpaceX Crew Dragon capsule. The founder of a payment services company and the mission’s leader imagined he might not go to space again. However, he and three crewmates are preparing for a far grander and more dangerous trip to space called Polaris Dawn. The mission aims to push boundaries and advance space technology.