Eye Problems From Space Affect At Least 21 NASA Astronauts 109
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How does microgravity affect your health? One of the chief concerns of NASA astronauts these days is changes to eyesight. Some people come back from long-duration stays in space with what appears to be permanent changes, such as requiring glasses when previously they did not. And the numbers are interesting. A few months after NASA [said] 20% of astronauts may face this problem, a new study points out that 21 U.S. astronauts that have flown on the International Space Station for long flights (which tend to be five to six months) face visual problems. These include "hyperopic shift, scotoma and choroidal folds to cotton wool spots, optic nerve sheath distension, globe flattening and edema of the optic nerve," states the University of Houston, which is collaborating with NASA on a long-term study of astronauts while they're in orbit.
Re:What can be done about this? (Score:5, Insightful)
aside from artificial gravity, nothing. No amount of exercise bike pedaling will save your optic nerves from being in zero G too long.
There isn't really any good reason to put people in orbit for 6 months+. Rotate them out every couple of months. Yes we needed data on long-term microgravity effects on the human body. We have them now, zero G does bad things to your body. So don't do it for extended periods.
Fly in the ointment is the expected trip to Mars, which will take 9 months to a year. Fortunately people like Zubrin have developed advanced technologies to deal with this. It's called a rope. Attach the Mars spacecraft to a ballast via a rope (they call it tether) and spin it until you get 1/3rd G. Problem solved.
Obviously... (Score:5, Insightful)
Obviously orbital habitats either need to be spun-up or contain living quarters located within centerfuges.
Re:What can be done about this? (Score:2, Insightful)
It is easy to create artificial gravity by spinning a cylinder and walking on the inner surface, using the centrifugal force. Like your washing machine does it. However these health problems are not related to gravity. Health problems relating purely to gravity are all muscoskeletal - atrophy of muscles from nonuse, and deterioration of bones from not being needed much, lack of stress on them.
The eye problems and heart problems come about from something else - intense cosmic rays. The space station is too friggin small to provide proper shielding. A rotating cylinder space station of 300 yard radius and half a mile length would be much better. Especially if you put many floors on it, as each floor serves as a radiation shield, and you could sleep suspended in a sleeping bag in the center weightlessness zone, the most shielded part. Of course it comes down to wall thickness, and for starters, you need at least two steel cylinders with small gap/lubricant sliding on top of each other, so in case of an iron-nickel meteorite projectile piercing through both going at 30 miles per second, and through all floors then exiting the other side, the sliding motion covers up the hole pretty fast, and does not leak the whole space station to vacuum quickly, and lets you evacuate to a different air locked segment while spacewalk outside repairs like thermite welding are under way, and the segment can be fully repressurized. The thicker the wall the better protection from cosmic rays, however, you don't want to go too thick, as the atmosphere down here on earth only protects so much, and the highest background radiation places like India from all that thorium, still have healthy populations. Without cosmic rays the rate of mutations and stillborn babies probably drops, but it also stops evolution, and new forms of beautiful or better people appearing on the scene. I wonder if there is a correlation between altitude of a city and number of stillborn babies, for a standard batch of people, such as Asians from Shanghai living in Lima, Katmandu, near the Dead Sea (below sea level), etc. Comparing indigenous people does not work as they may already be adapted to high background radiation, and in fact these high altitude Tibetan and Andes people might be better suited to be astronauts, because they've been under less insulation protections from the atmosphere above them than the rest of us, in a sense they have already been living closer to outer space, outer space is more their home than ours. However people living near simply high background radiation, such as thorium in India, at low altitude, fall under the same category.