It's interesting to think about:

The stated mission for the Space Race has often been "put a man in orbit", "put a man on the Moon", "put staff in the space station for X period".

But implicit in all of those mission designs has been the goal of returning the crew alive and in one piece. The record is rather favorable in that regard, and it's always a tragedy when we lose someone.

So that's one of the reasons a crewed Mars missions is a daunting prospect: because even with improved technology, it may be a one-way trip.