Apollo didn't go very far, and even then they had to get the McGuyver handbook out to prevent the Apollo 13 crew from suffocating when the unexpected happened. NASA have to learn how to expect the unexpected again, then we can go visit Mars and do the other things.
Not really to be honest, lives are lost by the thousands every day, lets be honest, building a completely replairable, replacements for every part ship that can make the journey there and back, WILL NEVER HAPPEN. You can't expect every unexpected outcome. Because what if they make that filter repairable, and they put 15 spares in, but they needed a 16th.
Be honest, brave people have a realistic expectation they might die.
Waiting 50 years to think of every eventuality at the cost of trillions over the decades to get one ship there safely, and there could STILL be a failure of any kind, is longer, far more expensive than sending simply the best ship you can make, hoping no one dies, but if they do, try again. You could make 100 pretty damned good reliable hopefully won't break ships, for the cost of one uber we've thought of everything, its the size of texas, theres literally scrap metal on board and a workshop so they can actually build anything they need en route, and its got deflector shields to boot. The difference is that one ship can still fail, the chances of 1 of the 100 pretty damned good ships making it, are hugely, massively better than the chances are sending a single ship.
We risk thousands of mens lives every single day in wars around the world, it would be tragic to lose anyone on a spacemission, or any mission for anything anywhere, but it will still happen no matter how much you spend and how good a ship you make.
But think what would have happened, how many people sailed from Europe to America, before Columbus made it, how much longer would it have taken to get there if they said, hmm, this ship doesn't have a fridge, I'm worried about scurvy, lets wait 300 years to do it.
Almost any major breakthrough of any kind has resulted in massive risk of life and lots lost before the breakthrough is made.
How many attempted heart transplants were done before one worked, how many people died from imperfect medications, before a correct version was found. how many lab rats/animals die to give us medications that save lives. How many people died in weapons designing and manufacturing, how many died in a nuclear reactor failure, that led to safer reactors, etc, etc, etc. It goes on and on.
I'm not for risking their lives willy nilly, but at some point you go.
AS others pointed out, the ships we sent to the moon, a million things COULD have gone wrong, they did do several times, yet they still made it in imperfect ships without everything they really could have done with.
When did the world become so namby pamby, you don't have to learn to expect the unexpected, you need to learn to live with the fact you'll make mistakes, because we're fallable, and thats how life is.
