Here's my design for solving this problem.<p>Instead of sending one rocket, you send two. You link them with steel cables. Then you rotate them around to generate the required gravity.
I wonder if you could bypass these issues with strength training machines designed for space. E.g a squat machine that pushes down from above, cable tension based arm movements, etc. I bet if you're clever you can probably have a small room that can get the essential exercises in and takes up a similar amount of room as a toilet
I wonder if it's really required to have 1g gravity in order to avoid this. It's much easier to artificially create, say 1/6g (moon) gravity by rotation than 1g, since rotational speed required is quite a bit slower.
This seems like a real problem for older astronauts who will never be able to gain that muscle back.<p>Muscle mass is so vital for long term health. 70-year-olds confined to bed rest for just two weeks have been observed to lose significant muscle mass that they most likely will never get back.<p>Obviously most astronauts are younger than 70. But they're also losing a lot more muscle mass and bone density.
One of the saddest parts of the science fiction novel _Aurora_ is that natural born human populations will have serious problems permanently separated from the larger ecosystem they're evolved for.<p>It's a valid hypothesis. Humanity would need to have an entire engineered biosphere to replace the biome living in our guts, our eyes, our . . everywhere. And anywhere we find that's close enough to Earth to live in, will have . . <i>something</i> else . . almost certainly[1] already there.<p>Kim Stanley Robinson isn't an easy read if you're on the other side of the political spectrum, but Aurora is comparatively free of his standard preachiness, at least in my ears. I actually disagree with his primary thesis of Aurora, and the novel suffers from some fundamental problems as a story, but the point is still salient. Humans will have to build their own Earth, wherever they end up, either out there or back here. I have a funny feeling we won't learn to treasure our own planet until we find out how much work it is to live on another.<p>[1] Particularly given the extraordinarily early date of the first Terran lifeforms. It doesn't seem to take too much to get the ball rolling, unless the panspermia theories actually turn out to hold some water.