An article I read over at New Scientist/Space made the claim humans aren't likely to ever conquer space because of the lack of gravity.
"One of the first things to be affected is the heart, which shrinks by as much as a quarter after just one week in orbit." The article makes many other claims that seem fairly damning of humans ability to live in space.
A common idea is to build a centrifuge for artificial gravity, but people have noted that if this centrifuge was on the smaller scale, ala 2001 A Space Odyssey, then the apparent gravity experienced by your head would differ noticeably from your feet, and much discomfort would ensue. Well, what about not having to deal with walking around, or standing up? What if the only way you were supposed to experience the artificial gravity centrifuge was by laying on your back against the outer wall, limiting the felt difference in gravity?
What if it was only a sleeping/exercise centrifuge? Picture the carnival ride "The Gravitron". You could lay on the outer ring of the centrifuge, flat against the wall, with a weight lifting system equipped around you for your arms, legs, and abdominals. The centrifuge would spin up to an apparent 1G, and then you could work out against gravity and sleep in gravity. The difference between the gravity felt by your nose, and by the back of your head, can't be significant enough to cause discomfort. Because this would be a strictly sleeping/exercise centrifuge, it could be quite small I imagine.
It seems like you might even be able to spin it up to greater than 1G. If a lack of gravity decays bones & muscle, and gravity helps prevent this, perhaps additional gravity would help even more? This centrifuge would only help prevent muscle & bone loss 8 to 10 hours a day. But who knows, that could still be a huge life saver. And it could be built tomorrow, unlike the fancy space tether designs for total artificial gravity we haven't quite figured out yet.
Furthermore, wouldn't grasshoppers make a fantastic food source on a space station? Grass can grow quite fast. And grasshoppers are packed with nutrition. If we're going to have vegetable gardens for oxygen and fresh food on the moon or other outposts, we should think of grasshoppers as an easy and efficient way of getting our protein..