The very first Apollo attempt killed three astronauts. We would need something different now because the cold-war-crazy days are behind us, and we don't push ahead with missions that might end up in casualties.

We do push ahead with missions that might end up in casualties. It's just a matter of risk tolerance.

It's impossible to say a space flight mission has 0% chance of casualty. It might be impossible to say that for virtually any activity involving humans.