What adverse effects does weightlessness have on the body?

Here is a scientific paper listing them all.

@Skaggfacemutt The answer to this question is that it wouldn’t work how people commonly think it would. Instead of adjusting we would simply create a habitat which included the correct pressure (and even extra gravity through centripetal force) to the extent as is needed to ward off serious ill effects. In the future we might be able to adjust through genetic modification but no-way-no-how are we there at this stage. We could have a moon colony, colony on mars, space-colony, etc with “current technology” but we wouldn’t be able to “adapt” with current technology in a single generation. There are people who are genetically able to withstand lower air-pressure such as people evolved on mountains. Some people might also have genetic abilities to survive low-gravity better as well but these aren’t “adaptions” we created for space but rather just some adaptions pre-existing on earth. It would take a long time to evolve a race (many generations) for truly different environments. There might be some drugs or medical treatments which would help that could be developed in a reasonable amount of time. For instance some drug might increase red blood cell count. ... but nothing will help as much as compressed air and artificial gravity.

There is some promising work on a protein that reduces calcium loss in mice to only 3%. If it’s the same with humans, that’s a major breakthrough.

The need is for us to get out there and keep studying using both animals and humans.

To @marinelife‘s list I would add an effect recently reported in the news (sorry no link): Slight swelling of the optic nerves (from fluid redistribution in the body) causes nearsighted astronauts to see more clearly and farsighted ones to have blurred vision. The long-term effects are unknown, though I’m not aware that anyone has gone blind from prolonged weightlessness.

@fluthercensors‘s suggestion that artificial gravity would avoid most of the problems seems sound. If a spacecraft were rotating at just the right speed to produce 1 g of centrifugal force (usually called “fictitious” force by physicists, but here an apt description what the body experiences), then space travel might not require too many other adaptations.

The trick is to make the radius of rotation large enough that people don’t feel vertigo or queasiness as they subtly change direction every time they move in a seemingly straight line & to minimize coriolis forces. A long tether between two equally massive ships rotating about a mutual center point should work. Sci-fi writers have explored this in detail.

Muscular weakness and some bone loss. It is not uncommon for astronauts to need bone supplements when they return from a voyage.

@gasman So does that mean if I go into space, I can ditch my glasses? Haha. I wish.

its really hard to get an accurate reading on the scale….?

@lonelydragon That’s exactly how they discovered the effect – astronauts reported they longer needed their glasses!