Comment Yes, I agree, here's my previous post (Score 1) 155
What level of gravity do humans need to THRIVE for long periods of time? (That is so that they do not suffer from bone density loss, cardio-muscular problems, etc.) Is it 1/6 gee (moon)? 1/3 gee (mars)? Or will humans need a full 1 gee to live and, eventually, safely REPRODUCE?
If the answer is humans need a full gee, then we might as well just resign ourselves to limiting our trips into the solar system to quick jaunts and robotic explorers. (While you *might* convince colonists to spend say an hour a day doing exercises to maintain their health, no way would you be able to make a fetus do them). We'll need to re-engineer humans before we can make a serious effort to colonize another world. (The only rocky planet with anything near our level of gravity is Venus and it is a hellhole). That's why the loss of the centrifuge planned for the ISS that would examine the effects of "partial gravity" (as opposed to the "micro-gravity" the ISS currently has or the regular gravity that we have) on biological systems was so disappointing. Literally it would have told us whether or not colonization of space was really feasible in the near future. (It probably wasn't going to be big enough to hold people but just seeing how partial gravity affected laboratory mice would go a long way to answering these questions).
Perhaps if we can dump the Ruskies, with the money saved with using Space-X's rockets we could build a decent centrifuge to make these (literally) VITAL studies. Maybe we don't even need to attach it to the ISS; just take two of Bigelow's(?) inflatable habs, add a cable and spin! (Just by changing the cable length you could alter the g-forces so no additional propulsion other than the initial thrusting would be required). But that's the deluxe model, you could just take the Dragon capsule and have a cable attached to its spent second stage and spin THAT (the center of gravity might not be in the "middle" but it should work fine). Keep it in orbit for a few generations of mice and dissect them when they return.
While we're at it, we should probably look into circadian rhythms... (but maybe mars, with it's 24-1/2 hour "day" is close enough).