If a large meteor hits Earth, the humanity organism will be glad it spread itself to Mars.
That's a possibility with Mars too, but a riskier return due to the distance.
"As we reported previously (Ronca & Alberts, 2002b), pre- and postflight body weights of dams and the body weights of the offspring used in these experiments were comparable across treatment groups. Within 48-72 hrs following landing, the rat dams that contributed offspring to the postnatal studies gave birth to healthy offspring."
People have feelings. Humanity does not.
But if you're going to give it feelings, a far more likely outcome is that a life-ending meteor will not hit the earth, and that the humanity organism would be much happier if it didn't waste its efforts on chasing a fairy tale, instead of fixing problems here, on Earth.
It boggles the mind that people worry about planet-killing meteors arriving over geological timescales, when the real danger - sustainability - is staring us in the face today, and needs action now.
When we build our own spaceships, we rapidly develop in miniature the sustainable tech needed to really fix earth.
We already have carbon dioxide scrubbers, we just need a vast clean source of energy in order to clean things up, and stop the pollution on net.
Probably fission is a good enough stop gap.
This will happen as soon as the incentive structures are there.
Engineering progress is helping, even if indirectly. Who knows what more energy efficient environment cleansing tech will he developed for spacecraft next. Or power sources, batteries, etc. Technology development is cumulative and crosses over domains.
Spacex is a spearhead rapidly innovating technology. Government mechanisms are a sort of discombobulated rising tide/ pasture of cows, or herd of scared sheep trying to stay on the grazing turf. Assuming gov’s do not get very much more organized, the better the tech, the easier choices the sheep have to make — win wins get things done. We could benefit greatly from tech advances such that gov gets win wins by making green choices. That way the incentives can tilt more favorably more quickly.
The problems of sustainability or climate change are about political will and priorities. They aren't something a single billionaire can solve. Focus on mobilizing, organizing, and educating voters if you want to do something about sustainability.
That's the appeal of dreaming about Mars. It's all vague, hand-wavy, loosey-goosey. It's like a software project, before the first line of code is written. To buy into the vision, you don't need to figure out how it has to work - you just need to have the hope that everything will fall into place, the code will be perfect and defect-free, and it's going to be way better then the system you are re-writing.
The only problem is that billions of people currently depend on the legacy system, and that the vague plan for the re-write calls for it to be carried out blindfolded, with a hand tied behind your back, and to make things more interesting, the language of choice is brainfuck.
If everyone had your attitude there would never be any progress. Imagine if someone told Newton "Why are you bothering with how things fall? Go solve the plague or something."
I have no vision of any Martian society. We can figure that out if we get there. Getting there is the interesting part right now.