Anyone going to Mars will have to stay there because the year-long trip would have so deteriorated their earthly bodies that they would probably die if they came back.
Then there is the rocket shot to leave Mars. No backup engineers, no supply chains, no modifications can be made. Rocket launches from earth require hundreds of tests and redundancies and ready supplies. Only one attempt can be made; fail and the whole crew dies.
Making it to Mars with our current technology is a long shot.
What is 100% however, is that Musk and Bezos launching all of their crap into earth orbit will soon create a Kessler Event (space junk crashing into other orbital space junk) that will effectively prevent anyone from leaving the earth for all time.
“Anyone going to Mars will have to stay there because the year-long trip would have so deteriorated their earthly bodies that they would probably die if they came back.”
The current endurance record for zero-G is 438 days, which is quite a bit longer than the 260 days required to reach Mars. That astronaut was able to walk from his lander to a vehicle immediately after returning to Earth. He fully recovered his endurance afterwards. All told, he was in space for 678 days across two missions, and lived to be 80 years old.
https://grokipedia.com/page/Valeri_Polyakov
On the topic of “the rocket shot to leave Mars”, the current SpaceX concept is a one-way trip for permanent colonists. I think it’s a good thing that they’ve refocused completely on the Moon in the shorter term, which will allow the perfection of lots of technologies related to Mars.
I don’t think Mars colonization will be practical until we have nuclear powered interplanetary spacecraft, which should cut trip times by a lot.
On the Kessler Event agitprop, in no way would it be a “for all time” issue. LEO space junk burns up, eventually. Folks are also developing technology to remove it on demand.